AIB has responded to reports that Poland's Financial Supervision Authority (PFSA) is examining the bank's agreement to sell its Polish banking assets to Spain's Santander.

'Certain doubts have come up and naturally we will check whether during the tender process any confidential information was leaked,' PFSA spokesman Lukasz Dajnowicz was quoted as saying by the AFP news agency.

'Various information is circulating on the markets. It must be checked. The PFSA has launched the investigation of its own accord,' he added.

AIB said the sale process was conducted in 'an entirely appropriate manner'. 'Any suggestion of irregularity in that process is without foundation,' it added.

AIB said on Friday that it was selling its 70% stake in Bank Zachodni WBK and a 50% stake in BZ WBK AIB Asset Management for a total of €3.1 billion. Santander won the tender against fellow European competitors, BNP Paribas of France and Poland's state-controlled PKO BP.

A report in Poland's Rzeczpospolita newspaper said AIB was alleged to have provided confidential information about BZ WBK's financial forecasts to Santander, a practice banned under competition regulations.

The paper also said that, during the negotiations, Santander was also advised by BZ WBK's official auditor.

The deal is subject to the approval of several authorities, including Poland's PFSA regulator and a green light from AIB shareholders.

The move to purchase AIB's 70% share in BZ WBK, Poland's fifth largest bank, is part of Santander's plan to buy up all remaining BZ WBK shares, traded on the Warsaw Stock Exchange, from minority stockholders.

Santander, Spain's largest bank, has been present in Poland since 2004 through its Santander Consumer division and it acquired AIG's consumer finance business last May. AIB is selling off the asset as part of a restructuring plan to meet targets set by the Financial Regulator.