West Ham are confident that the deal to move into the Olympic Stadium does not contravene domestic or European legislation and "categorically" stated that it does not constitute state aid.
The Premier League club are set to move into the London 2012 showpiece venue for the start of 2016-17 season, but the journey there has been a tortuous one, fraught with controversy.
Fresh questions were raised about the award of the 99-year lease to West Ham on Tuesday, when it was suggested the deal may contravene European state aid law.
The report suggests the failure of London Mayor Boris Johnson and the London Legacy Development Corporation to obtain prior approval from the European Commission before signing the deal opens up the possibility of challenges from anyone who feels disadvantaged.
That could leave West Ham facing a large compensation bill, but the club defended their position in a lengthy statement about the Olympic Stadium deal.
A West Ham spokesman said: "West Ham United is confident that its agreement with the LLDC complies with all relevant UK and European legislation and categorically does not constitute state aid.
"Indeed, the European Commission looked into a complaint in relation to our move to Queen Elizabeth Olympic Park in 2013 but 'decided not to further pursue' the matter.
"The club was selected as anchor concessionaire following a fair, transparent and robust process that was open to any group or organisation in the country.
"Out of the four proposals submitted, West Ham's was selected as it delivered a sustainable and viable future for the Stadium and, crucially, provided the best return for the taxpayer.
"The agreement with the LLDC will see West Ham make a substantial capital contribution towards the conversion works of a Stadium that it may only rent for up to 25 matchdays a year, pay a multimillion pound annual usage fee, as well as offering a share of food and catering sales from its supporters.
"The worldwide draw of hosting the most popular and watched football league in the world in such an iconic venue will add value to any sponsorship and commercial agreements related to the Stadium, which the public purse stands to further benefit from.
"It is clear that the linking of the naming rights to West Ham United generates real cash value for the LLDC.
"Without West Ham United, the Stadium would continue to cost the taxpayer millions of pounds a year.
"With us, the public purse will see a return on the hundreds of millions of pounds that were committed to build the Stadium, long before West Ham's association had begun."
West Ham's statement was echoed by the LLDC, who highlighted the Olympic Stadium's multi-use future.
"Our position has always been absolutely clear the arrangements for the Stadium at Queen Elizabeth Olympic Park do not constitute state aid," a LLDC spokesperson said.
"The Stadium will remain in public ownership after it has been transformed into a multi-use arena and has two concessionaires UK Athletics and West Ham United.
"This autumn it will host five matches of Rugby World Cup 2015, a Rugby League international and, in 2017 the IAAF World Athletics Championships and IPC World Athletics Championships.
"We have appointed an operator whose role is to programme other events in the Stadium including concerts and conferences, alongside the sport.
"We formed our position after taking specialist advice and it was shared with the Department for Business, Innovation and Skills and the Department for Culture, Media and Sport before we completed the open competitive process to find the main concessionaire and before we entered into contract with West Ham United."