Sepp Blatter has said he wanted the United States to host the 2022 World Cup. FABRICE COFFRINI/AFP/Getty Images

Sepp Blatter's support for the American World Cup bid should face more scrutiny, the head of Qatar's 2022 organizing committee said on Thursday in his latest expression of frustration at the focus on the probity of their winning campaign.

Qatar's FIFA backers have been criticized for seemingly ignoring the inspection report that highlighted the Gulf nation's fierce summer heat before still voting for the bid in 2010.

But Hassan Al Thawadi, secretary general of the Qatar organizing committee, believes then-FIFA President Blatter also had little regard for the assessment of the bid inspectors, given his unequivocal backing for the United States.

Since being forced out of office last year, Blatter has been providing more detail about the most disputed vote in World Cup history, including claiming there was a "gentlemen's agreement" for Russia's turn to be 2018 and for the tournament to return to the U.S. in 2022. Although Russia was successful, Qatar beat the U.S. 14-8 in the final round of voting six years ago.

"Blatter wanted the U.S. to win -- it's just fascinating that nobody is raising any concerns about that and looking into that one to start off with," Al Thawadi said. "But fair enough. I guess we will take the flak again."

Pressed further about Blatter at the Chatham House policy institute in London, Al Thawadi said: "He said he wanted the U.S. to win ... regardless of the merits of the bid, regardless of anything else."

The U.S. bid has not been accused of impropriety. Qatar has also denied any wrongdoing following FIFA investigations.

FIFA judge Hans-Joachim Eckert ruled in 2014 that any rule-breaking behavior by any bids for the 2018 and 2022 World Cups was "far from reaching any threshold" to require re-running the contests. No proof was found of longstanding allegations of bribes and voting pacts.

"We face these questions that other bids don't have to face," Al Thawadi said.

Providing an update on preparations, Al Thawadi said stadium construction is set to cost $8-10 billion, and that up to $200bn is being spent on wider infrastructure required to host the World Cup.

Working practices have come under sharp scrutiny since Qatar secured the World Cup for the region for the first time.

A recent report by Amnesty International implicated a World Cup stadium site in Qatar where migrant workers were said to have faced abuse that in some cases amounted to forced labor.

But World Cup organizers insist they have been acting to improve conditions for workers, and accelerated changes across the tiny nation.

"Monitoring enforcement mechanisms are being strengthened on a continuous basis, labor inspector numbers are being increased, site inspections are being increased, and scrutiny of recruitment agencies has been increased," Al Thawadi said.

"However change will not happen overnight and there are many issues on this matter that require further action, and more can be done."