ZURICH (AFP) - Global football's governing body Fifa on Thursday kicked off a crunch meeting amid claims of rights abuses by 2022 World Cup Qatar and wrangling over plans to hold the tournament in the winter.

Fifa's executive committee had already been scheduled to grapple with the issue of whether to shift the World Cup from its traditional June and July slot in order to escape the stifling Gulf heat, a plan which has angered European leagues that fear mid-season havoc.

But the pressure rose to fever pitch ahead of the two-day meeting behind closed doors at Fifa's Swiss base, after new charges of slavery-style treatment of migrant labourers working on Qatar's massive infrastructure projects for the 2022 tournament.

Four dozen Swiss and international trade union activists rallied at Fifa's gates in a leafy suburb overlooking Zurich.

They hammered home their message by brandishing referee-style red cards, chanting "Red Card for Fifa" and "No World Cup in Qatar without workers' rights".

Fifa communications chief Walter De Gregorio, who emerged to meet the demonstrators, said freedom of protest was crucial.

"But it's nothing new. We are very much aware of the situation," he told reporters, saying Fifa and Qatar were tackling the issue.

"Together, I think, we're going to find a solution to improve, or maybe to change, the situation that for sure, for everybody, is unacceptable," he said.

Fifa has held regular discussions with international human rights groups and unions for two years, he underlined.

"We're trying to put pressure on Qatar to change a situation which is unacceptable for all concerned. But I want to highlight that it's not Fifa against Qatar. We're all on the same page, trying to change the situation for the better of everyone. Qatar can change, and Qatar is very open to all discussions we're having," he added.

Qatar and Fifa have been in the eye of the storm after a report last week by British daily The Guardian on Nepalese workers at World Cup projects.

Quoting documents from Kathmandu's embassy in Doha, the newspaper said thousands of Nepalese - at 370,000 the second largest group of labourers in Qatar after Indians - faced exploitation and abuses amounting to "modern-day slavery".

The report said that dozens had died working in Qatar in recent weeks.

Beyond the fatalities, critics also point to the confiscation of passports, prevention of workers from leaving the country, withholding wages for long periods, and financial penalties for absence.

Other concerns include false promises on the nature of work, debts to recruiters or moneylenders, and crowded, squalid camps for labourers.

Gulf states' rules on foreign workers have faced criticism before, but the World Cup has intensified the spotlight.

Fifa expressed serious concern after The Guardian's report, while Qatar rejected the claims.