Johnny Ronan and Richard Barrett with taoiseach Brian Cowen. The developers could buy some of their troubled assets back from Nama

Developers whose land or property has been taken over by Nama will be able to buy back their assets despite assurances by the government when the agency was being set up that this could never happen.

The chairman of the Dáil's key spending watchdog expressed concern about the situation after it emerged that Nama could be powerless to stop developers – such as Johnny Ronan, Liam Carroll or Bernard McNamara – from setting up 'shell' companies or other financial vehicles to buy back the same loss-making assets which they have transferred to the agency.

This would allow them to benefit directly from any subsequent upturn in the property market by effectively buying up their own property at a knockdown price from Nama before selling it on at a bumper profit down the line.

Details of the legal loophole emerged at a meeting between the Public Accounts Committee (PAC), and senior officials from Nama last week.

During a lengthy question-and-answer session, Nama chairman Frank Daly – who is a former head of the Revenue Commissioners – noted that there was nothing in company law to stop any individual setting up a company to buy assets transferred to Nama by debt-ridden developers.

While the agency is not allowed to sell back a property to an individual developer – and has vowed to pursue borrowers until they have repaid all of their debts – it cannot prevent an individual developer setting up a 'shell' company to act on his or her behalf to do so.

In such a scenario, it could be virtually impossible for Nama to know the true identity of the purchaser involved once it was able to convince a lender or fellow investor to forward it the necessary funds.

Another option might also be for a wife, child or other relative of the developer in question to 'front' any prospective purchase on behalf of the developer.

By the end of next month, Nama will have acquired loans with nominal balances of €73bn at a cost of €30bn to the state.

Daly, who repeatedly stressed that Nama would vigorously pursue all available assets owned by developers, nevertheless noted he could "not come in here today and say that somewhere down the road" an individual would not come back to buy a property they previously owned.

Meanwhile, Michael McGrath, the Fianna Fáil TD and member of the Dáil's Public Accounts Committee (PAC), has taken the unprecedented move this weekend of writing to the Garda Commissioner, the Financial Regulator and the Director of Corporate Enforcement asking them to investigate the information provided by the banks to NAMA prior to the transfer of loans to the agency.

After raising concerns about the veracity of information provided by the banks to Nama at the PAC committee meeting in the Dáil last week, McGrath said, "It is now clear that if Nama had accepted in good faith the accuracy of the initial information supplied to it by the banks, the agency would have overpaid for the loan book by in excess of €20billion."

According to Nama it was informed by the banks that the average loan to value ration across the property and development loan book was 77%. In truth it was closer to 100%.

The banks also told Nama that 40% of the loans were 'performing' but Nama has discovered that only an estimated 25% of them were 'performing.' McGrath added, "Nama was initially given a misleading picture about the quality of the loan book. It is a matter for the relevant authorities to establish how this occurred, the reasons why and to consider what implications, under relevant legislation, may follow."