BERLIN (AFP) - German trade union chief Michael Sommer said Monday that world football governing body Fifa should pull the 2022 World Cup from Qatar unless the Gulf state improves conditions of migrants working on infrastructure for the tournament.

"We urge an immediate end to forced labour conditions or the World Cup be withdrawn from Qatar," the president of the Federation of German Trade Unions (DGB) Michael Sommer told Berlin national broadcaster rbb.

"We have launched initiatives in the UK, Sweden and Belgium. My French colleagues are particularly active in putting pressure on the French Football Federation," said Sommer, who is also president of the International Trade Union Confederation (ITUC).

"We're also increasing the pressure to ensure that something concrete happens," he said, noting that even Fifa have finally responded to the issue of working conditions in Qatar.

German Football Federation (DFB) chief Wolfgang Niersbach last month insisted that his organisation wanted to launch a concerted action with the DGB concerning the 2022 World Cup.

Amnesty International issued a report Monday calling on Fifa to press the Gulf state to improve labour conditions, alleging "alarming" levels of exploitation against the workers mostly from south or southeast Asia.

In a statement Monday, Fifa said they "firmly believe" in the positive impact of the 2022 World Cup by "improved labour rights and working conditions for migrant workers." Fifa underlined that its president, Sepp Blatter, visited Qatar on November 9 and received a "firm commitment" on the issue from its emir Sheikh Tamim bin Hamad al-Thani. "The state of Qatar is aware of various issues and has already started to react," Fifa said.

Doha, which rejects claims of slavery-style conditions on its construction sites in the world's wealthiest nation per capita, said it would investigate the report's findings.