Saudi Arabia, the likely host of the 2034 World Cup, is facing allegations of widespread use of forced labour among its vast migrant workforce, in a complaint filed at the UN’s International Labour Organization.

The complaint to the ILO alleges that migrant workers in Saudi Arabia are subject to a raft of labour rights violations including failing to pay wages, passport confiscation, illegal recruitment fees, debt bondage and preventing workers freely changing jobs.

The violations amount to “an epidemic of abuses”, according to the trade union that made the complaint, the Building and Wood Workers’ International (BWI).

It said they were evidence of forced labour, a modern form of slavery, which would put Saudi Arabia in breach of its obligations under the UN’s forced labour conventions.

Ambet Yuson, the BWI’s general secretary, said: “Saudi Arabia, where trade unions are banned, blatantly disregards international labour standards and fails to compensate migrant workers who have suffered abuses for over a decade.”

The trade union, which claims to represent about 12 million workers, is calling on the ILO to investigate the alleged violations. It is supported by organisations including Human Rights Watch (HRW), Amnesty International and FairSquare, which researches human rights abuses around labour migration and sport.

The complaint comes just months before Fifa is set to award the right to host the 2034 World Cup to Saudi Arabia, the sole bidder for the tournament.

The move is likely to put intense pressure on Fifa, which is already facing calls to bar the Gulf kingdom as the tournament’s host should it fail to comply with its human rights obligations.

According to Fifa’s bidding rules for the 2030 and 2034 World Cup, countries wishing to host the tournament must commit to “respecting internationally recognised human rights”.

Minky Worden, HRW’s director of global initiatives, said: “The complaint effectively says that Saudi has no meaningful protections against forced labour.

“This is a truly historic filing and may be the only significant roadblock to Fifa’s coronation of Saudi Arabia as the 2034 World Cup host,” she said. “Fifa must answer how it will assess and mitigate migrant labour rights risks as required by its human rights policy.”

Steve Cockburn, Amnesty International’s head of economic and social justice, said Fifa “could provide a much-needed spur for labour reform” by demanding binding human rights agreements before making a final decision on the 2034 tournament.

“By failing to do so, it would all but guarantee forced labour being at the heart of its flagship tournament,” he added.

The International Trade Union Confederation filed a similar complaint at the ILO against Qatar in 2014, which eventually led to a partnership between the ILO and the 2022 World Cup host to reform its labour laws.

The process led to the Gulf state largely dismantling its kafala (sponsorship) system – under which workers were unable to freely change jobs – and the introduction of a minimum wage, among other measures. But labour rights experts have questioned the impact of these reforms.

Like Qatar, Saudi Arabia is heavily reliant on migrant workers, largely from south Asia and parts of Africa, but on a far greater scale – there are more than 13 million foreigners in the country.

These numbers are likely to soar if the country is awarded the right to host the World Cup, with the tournament requiring major construction works, including new transport networks, hotels, training grounds and stadiums.

While Saudi Arabia began to introduce limited labour reforms in recent years, the BWI’s findings suggest migrant worker abuse remains widespread.

Its complaint includes a survey of 193 migrant workers who had worked, or are working, in Saudi Arabia. It found that 65% said their employer denied them access to their personal documents, such as passports, and 63% said they were unable to terminate their employment with reasonable notice or leave when their contract expired.

Fifa and the Saudi authorities have been approached for comment.