The Irish Independent has learned that Treasury Holdings donated the use of Battersea Power Station in London for the launch of the party's election manifesto in April 2010, despite owing banks hundreds of millions of euro.
The revelation raises serious questions as to why a company taken over by the State was allowed to provide a venue free of charge instead of renting it for a fee.
A spokesman for the company last night said that Battersea was used to host events on a regular basis, and was often provided free of charge to charities and other organisations.
He denied that providing the venue amounted to a donation to the Conservative Party.
"I think it's something that happens quite often," he said. "With (a donation to) any political party you have to declare it. We didn't give any money."
In relation to reporting the donation to NAMA, he added: "I don't think it's the type of thing that would arise.
"They didn't give any money and any money raised goes back into the upkeep of the building."
Returns submitted to the UK's Electoral Commission also show that two other high-profile developers in NAMA, Sean Mulryan and Derek Quinlan, made cash donations totalling almost €170,000 (£150,000) between 2006 and 2008 to the Tories.
Neither could be reached for comment.
The returns show:
•In September 2007, a company called Markland Holdings donated €114,000 (£100,000) to the Conservatives. The company is controlled Sean Mulryan and Paddy Kelly, who died earlier this year.
•In September 2006, Quinlan Private -- controlled by financier Derek Quinlan -- made a donation of €18,300 (£16,000). In February 2008, another donation of €35,000 (£30,500) was made.
•Just last year, Treasury allowed the party to use Battersea Power Station at no cost. The value put on the donation was £20,000 (€23,000).
A spokesman for NAMA said it did not micro-manage day-to-day spending of individuals or companies, and that developers were obliged to comply with submitted business plans.
"Our position on donations is that through the business planning process, we will seek to ensure that a debtor's business is being run as efficiently as possible in order to maximise repayments of their debts," he said.
Battersea Power Station is one of London's most iconic buildings and was immortalised when it appeared with an inflatable pig flying overhead on the cover of Pink Floyd's 1977 album 'Animals'.
A company called Real Estate Opportunities (REO), which is controlled by Treasury, bought the listed building for €600m in 2006, and was granted planning permission last December for a €6.5bn redevelopment of the site.
One of the NAMA top 10 developers, Treasury rents a portion of the site called the Boiler House as a venue.
A tent-like structure is stretched over a steel frame and a quarter of the ceiling is transparent, enabling guests to see the power station.
Britain's Electoral Commission's rules state that political parties are only obliged to report donations over £7,500 (€8,600) if made to party HQ, and over £1,500 (€1,700) if made to constituency offices.
This means that NAMA developers may have made other donations which were not reported.