Amnesty says workers at Khalifa International Stadium are forced to live in squalid accommodation, pay huge recruitment fees and have had wages withheld and passports confiscated.

It also accuses Fifa of "failing almost completely" to stop the tournament being "built on human rights abuses".

Qatar said it was "concerned" by the allegations and would investigate.

The government said the welfare of migrant workers was a "top priority" and insisted it was committed to systematic reform of Qatar's labour laws.

Last year the country pledged to makes changes to its "kafala" sponsorship system, under which migrant workers cannot change jobs or leave the country without their employer's permission.

But Amnesty warned the proposed reforms would make little difference and said some of the workers were enduring a "living nightmare".

"All workers want are their rights: to be paid on time, leave the country if need be and be treated with dignity and respect," said general secretary Salil Shetty.

Amnesty interviewed 231 mostly South Asian migrants - 132 working at the stadium and 99 on green spaces in the surrounding Aspire sports complex.

It said staff of one labour supply company used the threat of penalties to exact work from some migrants such as withholding pay, handing workers over to the police or stopping them from leaving Qatar.

This amounted to forced labour under international law, Amnesty said.

The Qatari government said its Ministry of Administrative Development, Labour and Social Affairs would investigate the contractors named in the report.

But Amnesty said every migrant it had interviewed had reported abuses of one kind or another, including being:

required to pay fees of up to $4,300 to recruiters in their home country to get a job in Qatar
deceived over the type of work and the pay on offer, which was sometimes half as much as they were promised
threatened for complaining about their conditions

One metal worker from India who worked on the Khalifa stadium refurbishment told Amnesty he was threatened by his employer when he complained about not being paid for several months.

(BBC News)