MPs have warned that the positive benefits for Wales from the London 2012 Olympics remain "uncertain".
The Welsh Affairs committee fears Wales will lose around £100m in lottery cash diverted to fund the landmark event.
The MPs' report voices concern over the lack of events being held in Wales and found little evidence of benefits to business from supply contracts.
The Department for Culture, Media and Sport (DCMS) said it was committed to spreading the benefits across the UK.
But the committee's chairman, Dr Hywel Francis, Labour MP for Aberavon, said: "It is not yet possible to say how, or even if, Wales will benefit from the 2012 Olympics and Paralympics.
"Hardly any events are being held in Wales, despite world class mountain biking and canoeing facilities."
The report follows an inquiry by the committee announced in November 2008.
During its investigation, it took evidence from sporting bodies, including the Sports Council for Wales and Disability Sport Wales, and the assembly heritage minister, Alun Ffred Jones, and the UK Olympics minister, Tessa Jowell.
Focusing on the issue of events, the MPs' report welcomed the fact that some of the games' football tournament matches will be hosted in Wales.
However, it is critical about the decision to host the canoeing and mountain biking events in England.
"The original bid missed an opportunity to locate events in Wales and in this period of financial uncertainty it seems misguided for the government to build expensive new venues for mountain biking and the canoe slalom when Wales already has highly suitable facilities," states the report.
The MPs say they believe Wales can still benefit from hosting pre-games training camps, with the Australian Paralympic team already signalling its intention to base itself in Wales.
"There is a huge potential for Wales to make a significant contribution to the 2012 Games, in particular its development and promotion of disability sports," added Dr Francis.
He said Australia's decision showed that Wales has "first class sporting facilities" and it will raise Wales' profile around the world.
Former paralympian Dame Tanni Grey-Thompson said there was still time for Wales to benefit from the games and defended the decision to organise a tight-knit event around the London area.
Speaking on BBC Radio Wales Dame Tanni said: "Once the games were won I think there was an expectation that everything was going to start straight away. The way it works, especially with the sporting side, is it's only going to really start kicking in two years before the games, next summer.
"The reality is that the sports have to be, as far as possible, within close proximity to the host city.
"The idea is that they want as many of the athletes as possible to be able to stay in the Olympic and Paralympic village and then travel from there to the venues, which logistically just doesn't work (with Wales).
"Ultimately London won the games and they have to be as much as possible around London and it's always been for the other areas to pick up other bits where they can."
Concerns about the loss of £100m in lottery funding are also highlighted by the report.
"This will have a long term impact on grassroots sporting projects," claims the report's findings.
However, the report accepts that Wales has benefited from its own regeneration projects in the past, including the redevelopment of Cardiff Bay.
But the MPs insist that following the games, the level of lottery funding for Wales must be addressed.
"There is a real danger that Wales will end up losing out completely if diverted lottery money isn't recouped quickly," added the committee's chairman.
The MPs make a string of recommendations following their investigation.
Included in their conclusions are a request that marketing for the Ryder Cup golf tournament being held in Newport in 2010 is used as a platform to boost tourism in Wales during the Olympics.
The committee also calls on the DCMS to establish direct links with the assembly government in the run-up to the games, to ensure benefits can be maximised for Wales.
Finally, the report calls for educational and cultural resources to be made available in the Welsh language as soon as possible, to ensure "the whole Welsh population can be engaged with the games".
Commenting on the report, a spokesperson for the DCMS said: "We welcome the Welsh Affairs Committee report and will respond fully in due course.
"The (UK) Government is committed to ensuring that the benefits of the 2012 Olympic and Paralympic Games are felt across the UK, including in Wales."