Fifa's sponsors must challenge soccer's world governing body over human rights abuses at the 2022 World Cup construction sites in Qatar, pressure group New Fifa Now and international workers' unions said on Monday.

New Fifa Now will work alongside the International Trade Union Confederation (ITUC) and UK Trade Union Congress-backed group PlayFair Qatar to rally Fifa's official sponsors over the rights of workers employed on World Cup construction sites.

Jaimie Fuller, chairman of Swiss-based sportswear company SKINS, the "official non-sponsor" of Fifa, told reporters he had written to eight of the governing body's sponsors -- Adidas, Gazprom, Hyundai, Kia, McDonalds, Budweiser, Coca-Cola and Visa.

In the letters, Fuller accused the sponsors of "contravening their own values and principles" by contributing significant sums of money to Fifa and thereby providing "implicit support" for working practices and conditions in Qatar.

"We are calling on these sponsors to stand up and do the right thing," Fuller said at a presentation in London.

"We are demanding that these sponsors come and distance themselves from what's been going on.

"We don't want sponsors to withdraw their support from Fifa, we don't want them to take their sponsorship away, we don't want them to take their money away.

"But we do want them to use the power of their money to get reform done."

Fuller, an Australian businessman who previously led the "Change Cycling Now" lobby group following a series of doping scandals, said he had not received a response from the sponsors but invited their CEO's to visit the work camps with him.

Fuller also showed footage he had obtained after being smuggled into several workers' labour camps in Qatar.

He criticised the Gulf state's "kafala" system of work sponsorship, whereby employers effectively control a labourer's freedom to leave the country.

Fifa released a statement saying it would continue to ensure more was done to improve working conditions.

"Fifa has repeatedly urged the Qatari authorities to ensure decent conditions for migrant workers in the country," it said.

"There have been significant improvements and these efforts are ongoing; but everyone recognises that more needs to be done and we continue to pursue this both with the local authorities and by working with international organisations." – Reuters