Banks are refusing to share information with one another as they prepare to meet government and NTMA officials to hammer out the details of the new National Asset Management Agency (NAMA) in the coming weeks.

Banking sources have told the Sunday Tribune that banks are pursuing their own agendas on the discounts, or 'haircuts', to be applied to the €90bn in toxic loans which are being transferred to NAMA to allow the banks to resume normal lending.

In the discussions, bank executives have already imposed the precondition that they do not want to hold discussions in the same room.

As the banks have taken a bilateral approach, the Irish Banking Federation (IBF), their main lobbying group, has been effectively sidelined with no direct engagement with the government or the banks regarding the structure or details of NAMA.

The IBF is seeking a full briefing from the chief executive of the National Treasury Management Agency (NTMA), Michael Somers, who is overseeing the setting up of NAMA, but the group will not be representing the banks in talks either with the Department of Finance or the NTMA.

One concern is that the interests of IBF member banks outside the government remit, such as Ulster Bank and Bank of Scotland Ireland, diverge widely from Irish banks whose assets are being confiscated.

The government is expected to deal with AIB and Bank of Ireland first, possibly as soon as this week, as assets from the big two banks will make up an estimated 60% of NAMA. Analysts have warned that haircuts exceeding 15% could force the government to take majority stakes in the banks to shore up depleted capital, leaving them in a situation like Royal Bank of Scotland, which has only a rump 28% in private ownership.

Sources said the whole process should be complete by June, although there is a potential roadblock on 13 May, when AIB holds its agm and egm to decide whether to accept the government's €3.5bn capital injection. The entire board is also up for re-election that day and there is no guarantee chief executive Eugene Sheehy will survive.