The true number of Indonesians struggling in the industry was likely to be much higher, it added, with more than 1,450 of them sent this year by a company called AG Recruitment to work on six-month seasonal worker visas.

An embassy official told The Guardian newspaper that initially people “started coming to us with problems about the targets on farms.”

But the official added: “Currently, most people are contacting us because there’s no more work at the farms. They try to transfer, but AG tells them there’s no other work.”

One worker told The Guardian he had borrowed £4,650 ($5,700) in Java to pay an agent to take him to the UK, but that his job at Castleton Farm in Scotland paid only about £200 per week. When he was dismissed after just two months he still owed £1,700.

Ross Mitchell, managing director of Castleton Fruit Ltd., said the farm had employed 106 Indonesian workers this year, 70 of whom were still on site, working an average of just under 42 hours per week, with an average weekly gross pay of about £450, excluding costs such as accommodation.

He added he was “very concerned” about “payment demanded by third-party agents” and that the company relied on “approved agents to have carried out due diligence to ensure that the workers are not paying excessive fees.”

“We had hoped the relevant bodies would have dealt with this issue,” he told The Guardian.

An investigation by the paper in August revealed Indonesian workers were regularly taking on debts of up to £5,000 to work in the UK for a single fruit picking season.

AG Recruitment, which has no presence in Indonesia, used Jakarta-based Al Zubara Manpower to source workers, which in turn used third-party brokers who charged the high fees to prospective workers, The Guardian said.

AG Recruitment denied any wrongdoing or knowledge of the practice, but has since been investigated by the Gangmasters and Labour Abuse Authority, a UK government agency.

A GLAA spokesperson told The Guardian: “Where there are allegations of labor exploitation we will investigate and take appropriate action if our licensing standards are not being fully adhered to … Scheme operators are fully aware of their responsibilities to workers.”

AG director Douglas Amesz said: “Workers should never pay fees to anyone to receive a job in the UK; this is UK law. However, unfortunately this is not law in all the countries we have historically recruited from so we are actively working to educate citizens abroad that they should never pay anyone fees to receive a job in the UK or anywhere else.”

Yulia Guyeni, director of Al Zubara, said: “We send workers based on the request from AG. We only charge based on the placement agreement the workers signed.

She added: “It is not our responsibility (to check the debts of workers) as we do not encourage them to have debt. They are old enough and should be responsible to realize the consequences of debt.”

Castleton Farm supplies fruit to some of the UK’s biggest supermarket brands. In a statement, the British Retail Consortium said the supermarkets “are concerned by these allegations and are investigating as a matter of urgency.”