The commission set up to investigate the collapse of the banks -which has brought the country close to bankruptcy - has ruled that it will not answer questions about the professional background of its investigators.

The commission, led by Peter Nyberg, the former Finnish finance official, said it would not answer any questions about the roles played in earlier careers by the investigators or whether the commission's appointees worked with bankers whose lending practices would now be the subject of investigation.

The Sunday Tribune asked the commission whether its recent appointee, Pat O'Mahony, a former head of AIB branches in the mid-1990s, had at any time supervised Eugene Sheehy, the former AIB chief executive who had worked around the same time as a senior branch manager in a Dublin city centre branch.

The Irish Times reported last week that among the team assisting Nyberg was one-time head of AIB's branch network O'Mahony, who left AIB in 1996 to develop property.

A spokesman said the committee had "made quite clear" it would not comment on any matter regarding its commission. It would neither "confirm nor deny" that O'Mahony had supervised or worked with Sheehy.