Northern Ireland police opened a criminal inquiry on Wednesday into a property sale by Ireland’s state-run “bad bank”, the National Asset Management Agency (NAMA), after concerns were raised in parliament.

The inquiry relates to the 1.3 billion pound (around $2 billion) sale last year of NAMA’s entire portfolio of loans belonging to Northern Ireland-based debtors to U.S. private equity firm Cerberus Capital Management, the agency’s largest deal to date.

NAMA is one of the world’s largest property groups having paid a total of 32 billion euros to purge local banks of risky loans worth over double that amount following a crash that forced Ireland to seek an international bailout.

“We believe that there is sufficient concern in relation to potential criminal activity, surrounding the property deal, to instigate an investigation,” the Police Service of Northern Ireland (PSNI) said in a statement.

Mick Wallace, an independent member of parliament in the Irish Republic, claimed last week that 7 million pounds which had been moved from a Belfast law firm involved in the deal to an account in the Isle of Man was “reportedly earmarked for a Northern Ireland politician or political party”.

He has not given any more details.

NAMA, which will appear in front a parliamentary committee to discuss concerns over the deal on Thursday, has said it sought and received confirmation from Cerberus that no fee was payable by Cerberus to any person connected with NAMA in relation to any aspect of the sales process.

Cerberus has said that no improper or illegal fees were paid by it or on its behalf.