Thousands of migrant workers in Qatar are still being exploited despite repeated promises to improve workers’ rights in the lead-up to the 2022 World Cup, according to a new report by Amnesty International.

The Amnesty investigation into three Qatari companies involved in construction and cleaning – Hamton International, Hamad bin Khaled bin Hamad and United Cleaning – found that at least 1,620 workers had submitted complaints after their wages were stopped for several months before their contracts were ended.

While some workers were eventually given part of their wages in exchange for dropping their cases, hundreds went home with nothing and none received compensation through a committee meant to settle labour disputes.

Among those quoted in the 52-page report – titled “All work, no pay: The struggle of Qatar’s migrant workers for justice” – was a Kenyan employee of United Cleaning who told Amnesty: “For five months I had to live with very little food and no salary. My family was really affected. Tears come to my eyes when I remember where we used to go to find food – in the bins. The company owes me a lot of money which they refuse to pay me.”

Amnesty believes the true scale of the problem is likely to be far bigger, with the US State Department estimating that more than 6,000 workers submitted complaints to Qatar’s new Committees for the Settlement of Labour Disputes last year.

The Qatari Ministry of Administrative Development, Labour and Social Affairs told Amnesty it helped to negotiate many of the settlements and provided food and generators at workers’ camps. None of the three companies investigated responded when presented with Amnesty’s findings.

Stephen Cockburn, Amnesty International’s deputy director of global issues, told the Guardian the report showed that for all Qatar’s promises of labour reform, the rhetoric did not match the reality on the ground.

“Despite the significant promises of reform which Qatar has made ahead of the 2022 World Cup, it remains a playground for unscrupulous employers,” he said. “Either the reforms are being done very slowly, or they are not being implemented properly or they are not being done at all. As a result of that there are still thousands of workers who are not being paid properly, they are not getting justice, or are living in poor conditions.

“We all know that as big tournaments come and go the window of change closes a little bit. What is being done for workers is not what is being promised. Promising reform is not actually the same as delivering it.”

Meanwhile, a spokesman at the Government Communications Office of the State of Qatar insisted the country would deal with any problems raised in the report. “We are aware of a recent report published by Amnesty International concerning the status of workers in Qatar,” he said. “Qatar has made substantial progress on labour reforms. We continue to work with NGOs, including the International Labour Organisation, to ensure that these reforms are far-reaching and effective. Any issues or delays with our systems will be addressed comprehensively. We have said, from the outset, that this would take time, resources and commitment.”