The secretary of the International Trade Union Confederation has accused FIFA of being in "conspiracy" with the Qatari authorities over "slave labour" conditions faced by migrant workers building facilities for the 2022 World Cup.
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Sharan Burrow said world football's governing body had "failed" after The Guardian reported that Nepalese migrant workers' lives were being put at risk during the emirate's preparations.
The newspaper obtained documents from the Nepalese embassy in the Qatari capital, Doha, which showed that at least 44 workers had died over two months in the summer. The deaths attributed to heart attacks or heart failure in searing summer heat, as well as workplace accidents.
Its investigation found evidence of forced labour on World Cup infrastructure projects, while it has also been alleged that pay has been withheld and passports confiscated to prevent the workers from leaving.
FIFA said it was "very concerned" by the findings and would discuss the issue at its executive committee meeting next month after contacting the Qatari authorities.
But Burrow said the organisation was not doing enough to address what was happening, adding to the Associated Press: "If FIFA really were serious, then their power to hold the World Cup with decent work or to withdraw it would be enough for the Qataris to sit down and talk."
In a letter to FIFA president Sepp Blatter last week, she said "several hundred migrant construction workers die each year in Qatar" and warned that the huge range of construction projects being launched would see the situation become even worse if action was not taken.
And she added that, after a meeting in November 2011, FIFA had said it would address the situation -- but had still not done so.
The problems with the extreme summer heat -- already a major talking point amid plans to move the World Cup to winter for the first time in its history -- are thought to be posing substantial health risks, with some workers claiming they have been refused free drinking water.
Qatar, whose immigrant workforce stands at 90 percent, is accused of exploiting a situation that sees Nepalese workers paying recruitment agents to secure work in the state and then being left powerless to escape the conditions.
Over the summer, Nepal's ambassador to Qatar, Maya Kumari Sharma, sparked a significant controversy earlier this summer when she said that the state had become “an open jail” for workers from her homeland.
Jim Boyce, the FIFA vice-president, joined calls for the body to launch a full investigation into the reports, which he said had left him "appalled and very disturbed".
And the situation drew condemnation from British politicians, with Labour's shadow sports minister, Clive Efford, saying the thought of "multi-millionaire footballers playing in a country that has been built on these sorts of human rights records" was "obscene".
Conservative MP Damian Collins said the English FA should consider a boycott of the 2022 competition if FIFA failed to take decisive action.
The Qatar 2022 Supreme Committee, responsible for the organisation of the tournament, said in a statement that it was "appalled" by the report's findings.
"There is no excuse for any worker in Qatar, or anywhere else, to be treated in this manner," the statement said. "The health, safety, well-being and dignity of every worker that contributes to staging the 2022 FIFA World Cup is of the utmost importance to our committee.
"We firmly believe that all workers engaged on our projects, and those of the other infrastructure developers in Qatar, have a right to be treated in a manner that ensures, at all times their well-being. This is our top priority as we begin to deliver on the promises made in our bid to host the 2022 FIFA World Cup in Qatar."