Some of the world’s leading tea manufacturers, including Tetley and Lipton, are examining working conditions on the plantations of its Sri Lankan suppliers, following a Guardian investigation.

Two global trade-certification schemes, Fairtrade and the Rainforest Alliance, are also conducting inquiries after it was revealed that some workers on 10 certified estates could not afford to eat and were living in squalid conditions.

Tea pickers claim that estate owners failed to support them during the country’s unprecedented economic crisis, which has seen prices of food, fuel and medicine soar, without wages rising to match. The pickers reported supervisors refusing to pay them what they were owed and incidences of verbal abuse.

Some of the pickers said they had so little money that they were having to skip meals and felt forced to send their children to work.

Tetley said it had suspended work with some central Sri Lankan estates while it conducted its own inquiries. Ekaterra, which owns Lipton and PG Tips, said it was in contact with the Rainforest Alliance over the findings. Yorkshire Tea, another company that sources tea from the estates the Guardian visited, said it was speaking to the plantations concerned.

Image: Rangasamy Puwaneshkanthy, a plantation picker, lives in these hills above a tea estate. She has taken out loans to pay for food

More than 300,000 people work in Sri Lanka’s tea plantations, which are mainly in the mountainous Central Highlands. In 2022, the industry generated £1.079bn in exports.

Tea pickers have been struggling since the country was plunged into an economic crisis after a disastrous ban on chemical fertilisers in 2021, which decimated tea yields and caused production to fall to a 26-year low last year. Workers must pick at least 18kg (40lb) a day to earn 1,000 Sri Lankan rupees (about £2.60/$3.25) – a fee set by the government’s wage board in 2021. If they pick less, they get a lower rate for each kilo.

The depreciation of the rupee has caused the average daily wage in the sector to fall in real terms over the 24 months to February 2023 from £3.90 to £2.20. A bailout from the International Monetary Fund in March saw the figure bounce back slightly to about £2.60. But inflation, which hit an all-time high of 86% in September, has kept food prices high.

In January, the UN World Food Programme estimated that 44% of families in tea estate areas were food insecure – twice the figure of urban districts.

Workers claimed some estate supervisors have tried to underpay workers. Lakshman Devanayagie, 33, said: “Even if we pick good tea leaves, they will say it’s not good enough, and they will tip it out, or that they are going to cut our pay.

“If we give them five kilos of tea leaves, they will only pay us for two or three. When we ask them, they say, ‘we’re doing as we’re told, so why don’t you do as you’re told?’,” she said, adding that she felt suicidal at times.

Rangasamy Puwaneshkanthy lives with her husband and three children in the hills above one tea estate. She said has had to take out loans to pay for food and regularly missed meals, adding that she often chose to forgo buying sanitary towels so she could buy food for her children.

Image: Lakshman Devanayagie and her son at their home. Many workers live in tiny homes with no running water or toilets

“If there’s no food at home, then I don’t take any to work. I tell them [supervisors] I’m going home for a bit and then come back, because I can’t watch other people eating,” Puwaneshkanthy said.

She said pressure to pick quickly meant that she did not have time to watch out for leeches, which are common in the damp climate. Last year, her leg became infected from one and she had to walk for an hour to see a doctor because she could not afford a rickshaw ride.

“If we stop to pick the leech off, then we’ll be one kilo down – that’s how we’re thinking when we work,” said Puwaneshkanthy.

“We don’t know what to do. We’re working on the estate, but we have no salary. What are we meant to do?”

Another worker, Subramaniam Sathyavani, 40, said she felt dehumanised working on the estate. “We give our blood so the managers can live comfortably,” she said.

The tea estates are run by companies that lease land from the government. Most workers are Malayaga Tamils, descendants of indentured labourers brought from southern India by British colonisers. Most still live in the tiny homes built by the British, which are now owned by the plantations.

Some have no running water or toilets, and workers say they are forced to defecate in nearby rivers. Puwaneshkanthy’s eldest son says sometimes he doesn’t go to the toilet because he’s too scared of the snakes and leeches in the water. One woman said her husband had died after drinking contaminated water.

While they are not forced to stay on the plantations, there are few other job options in the area for the tea pickers, and many have limited education.

The rural location means workers have little choice but to use amenities provided by the estate, such as childcare, the costs of which are deducted from their wages. The Guardian has seen a number of wage slips that showed monthly deductions of 50% or more.

At least once last year, Puwaneshkanthy said, she was left with nothing at the end of the month after all her bills had been deducted.

“If we work 22 or 23 days, because of all the cuts we only get about 15, 16 days’ worth of pay. And then when they cut everything… they give us, there’ll be no salary left,” said Puwaneshkanthy, who in January left the estate to work 75 miles away as a housemaid in Colombo, where she can earn more money.

Jeevan Thondaman, Sri Lanka’s minister for water and estate infrastructure, said the findings showed “exploitation in its finest form”.

He said: “We have to find a way to expedite or accelerate this process of giving them decent work. And I have a feeling we can do that by involving international agencies [like the] UN, Flocert [a trade certification body] and Fairtrade.”

Thondaman said some plantations had lied and had “bullshitted” to all these foreign organisations that they were “ethical” to get funding. He wants the government to break up the estates and lease land to workers to grow their own cash crops, giving them greater control.

Fairtrade, which certified three of the plantations visited, said it had referred the Guardian’s allegations to its independent certifier, Flocert, and the Fairtrade protection committee, which oversees the safety of children and vulnerable adults.

In a statement, it said plantations were obliged by the Fairtrade Standard for Hired Labour Organisations to adjust wages to keep pace with inflation.

“Fairtrade takes allegations of worker mistreatment very seriously. Indeed, improving the livelihoods of workers in challenging regions is one of the reasons that Fairtrade was established,” it said.

The Rainforest Alliance, which has certified nine estates, said it was “deeply concerned by the allegations”.

“We take this matter very seriously and will be conducting our own investigations, as is our usual process,” said Madhuri Nanda, the alliance’s south Asia director. “These investigations will inform next steps and appropriate action, which could include suspension or cancellation of the certificates of the tea estates in question.”

Lalith Obeyesekere, secretary general of the Planters’ Association of Ceylon, the body that represents the plantation companies that the Guardian visited, said claims that salary deductions left workers with no wages were “unsubstantiated”. Any deductions had to be authorised and not exceed 50% of a worker’s wage. He said employees could file grievances if they believed too much money had been deducted but no complaints had been reported by members.

Obeyesekere said plantation workers got 14 days of paid holiday and 14 days’ sick leave a year, as well as bonuses, three months’ paid maternity leave, and free maternal and childcare until the child was five. Workers were also entitled to allowances of milk powder, flour and rice, and the children received free medicine and vaccinations.

He said investments were being made to improve amenities, including housing, sanitation and hygiene facilities. He added that the industry was exploring all possible options to mitigate the worst effects of the economic crisis for employees and that increasing wages was a top priority for the association. However, its members could only pay employees out of revenues and was calling for an end to the current payment system.

In August, Sri Lanka’s court of appeal dismissed a petition by plantation owners seeking to reverse the 2021 wage increase.

Thondaman said he would lobby the wage board to increase pay. He also said new technology, such as digital weighing machines, which have already been installed on a few estates, should be rolled out more widely.

However, Palani Digambaram, an MP from the National Union of Workers, who grew up on tea estates, said people were working as “slaves, without proper food or salaries”.

“If there are no tea plantations, I’ll be happy. Do our people only have to work on tea plantations?” he said. “With leeches and snakes biting them, tigers and this and that coming, just having to pluck tea leaves, what will their life be like? Those women are suffering.”