AIB Chief Executive David Duffy has said that the bank is writing to all people of a senior level who were involved in critical roles from late 2005 to late 2008 in relation to forgoing a portion of their pensions.
He said the bank had sent out an initial set of letters to deal with more "obvious people" and it would take another four to six weeks to send out all the letters.
It is understood upwards of 15 people will receive letters.
Mr Duffy said AIB had held discussions with one individual and their advisor.
"We are not acting as judge and jury on the issue, our employees are suffering from reduced pensions and other benefits as a result of the bank collapse.
"The public is suffering the consequence of investing that amount of capital in the bank."
He said taxpayers’ money was not used to shore up the pension fund.
Instead, the bank sold income-generating assets to the pension fund.
That deal reduced a deficit in the pension fund and avoided the prospect of compulsory redundancies, Mr Duffy said.
The bank said it has no legal authority to force the individuals to hand over some of their pensions.
However, it said it believes there is a moral argument for them to do so.
It is understood former CEOs Colm Doherty and Eugene Sheehy have been written to by the bank.
Speaking in the Dáil, Taoiseach Enda Kenny said he hoped that retired the former directors would make decisions in regard to the level of pensions they receive following the letter.
He added that the transfer of €1.1bn of loan assets into the pension fund at AIB was to deal with the deficit which came as a result of 2,500 people taking voluntary retirement from the bank.
If the transfer had not gone ahead, he said, then the bank would have to have had forced redundancies.
Mr Kenny said he would not be supportive of a further transfer of funds to deal with any pension deficit for people who have already retired and are in receipt of extraordinarily high pension income.
The Taoiseach was responding to questions from Sinn Féin.
Mr Kenny said a pension reputed to be of the order of €500,000 to be truly extraordinary and there was a moral responsibility on individuals to deal with that.
He said he did not know the individual contractual arrangements.