The Qatar 2022 World Cup organisers have for the first time hit back in detail at the widespread corruption allegations that put their grip on the event at risk, insisting they are "baseless and riddled with innuendo".

Going on the attack, the Qatar 2022 organising committee said that the bribery claims were tactical leaks designed to interfere with the independence of an ongoing investigation by former New York attorney Michael Garcia.

Having previously insisted Mohamed bin Hammam, the disgraced Qatari former Fifa executive at the heart of the claims, had no "official or unofficial" role with the bid, organisers have now tried to clarify their relationship. Bin Hammam was forced out of football after it emerged he had paid bribes to win support for his bid for the Fifa presidency in April 2011. The Sunday Times has linked payments from a $5m slush fund to football officials in Africa to Qatar's bid to host the 2022 World Cup, but Qatar's supporters insist those payments were related to his presidential bid.

The Qatari organisers said that they had "never denied we had a relationship with Mr Bin Hammam" and that, as he was a voting Fifa executive and the Asian Football Confederation president, it was "important for us to maintain a working relationship with him".

"But let us be clear: Mr Bin Hammam is from Qatar, but he was not a member of Qatar's bid team," they said.

"None of this was improper. We hoped, of course, that Mr Bin Hammam would support our bid. But we hoped for the same from every executive committee member."

The lengthy response is designed to pre-empt a new wave of claims in the Sunday Times expected to focus on the relationship between the organising committee and Bin Hammam in the period after the bid was won and before he was expelled.

"The constant stream of allegations that have been released to media outlets on the cusp of our interviews with the chairman of Fifa's ethics committee investigative chamber do not implicate our bid," it claimed. "They are instead a series of tenuous links that attempt to assume guilt by association."

It said the leaks were timed to coincide with important dates in the Fifa calendar, such as last week's Fifa congress in São Paulo, and were designed to undermine Garcia's investigation. Garcia has finished his investigation into the controversial 2018 and 2022 World Cup bidding races and has promised to deliver his report by mid-July. He told the Fifa congress last week that he had been in possession of the source material behind the Sunday Times stories "for some time". But journalists at the paper believe there is more material in their cache of "hundreds of millions" of documents that he has yet to consider.

The head of the adjudicatory chamber of Fifa's ethics committee, Hans-Joachim Eckert, is expected to publish his final conclusions in September.

It is understood that the Qatari organising committee are preparing to fight any attempt to strip them of the World Cup in the Swiss courts, having already begun building three of the stadiums required. They admitted "aggressively marketing" their hugely well resourced bid but insisted they broke no rules.

The Qatar 2022 organising committee also again claimed hosting the World Cup would act as a catalyst for change in the region.

"We pledged that this tournament would be a catalyst for accelerating improvement in our nation and the region," said the statement.

"One example of this is our comprehensive engagement on the issues we face in regard to labour. We implemented worker welfare standards. This is spurring change and engagement."