AIB Chief Executive David Duffy has defended his assertion that 20% of the bank's mortgage customers in arrears are making a conscious decision not to pay their home loans.

He was speaking at the Oireachtas Finance Committee this afternoon.

Mr Duffy said statements filled out by customers in arrears showed that one in four had enough income to pay.

He added that one in four of AIB's buy-to-let loans had no repayments in the past six months.

Mr Duffy claimed that meant that rent was being diverted from the bank.

He said 2,000 customers in arrears have deposits greater than the amount of the arrears.

Sinn Féin Finance Spokesperson Pearse Doherty asked Mr Duffy about an example of an individual setting aside money in a deposit account to pay for their children's college fees.

Mr Duffy said if somebody had decided to put money aside that meant they were not paying their mortgage.

Earlier, Mr Duffy told the committee that AIB has completed 4,400 permanent solutions for people in mortgage arrears.

He said that the bank has exceeded its Central Bank targets on mortgage arrears.

Mr Doherty told Mr Duffy: "You have not exceeded the targets. You have not reached the targets."

Mr Duffy responded: "You make a lot of statements I disagree with."

Mr Duffy said that AIB's engagement with customers in arrears had increased by about 30%, while AIB continues to dedicate significant resources, in terms of personnel and training, into tackling the arrears issue.

The committee was also told today that AIB has written off €38m in residential mortgages this year. This compares to a figure of €55m for all of last year.

Mr Duffy told the committee that if the bank was to write down all mortgages in negative equity it would cost "significantly more" than the entire capital of the bank.

The rest of the country's bank chief executives, including Bank of Ireland's Richie Boucher and Permanent TSB's Jeremy Masding, will also appear before the committee as the week continues.

The bank bosses will face questions from TDs about their plans for sustainable and long-term solutions for home owners in mortgage arrears.

Committee Chairman Ciarán Lynch said that when the banks were last before the committee, there were no specific targets in place to provide solutions for homeowners in arrears.

"Those targets are now in place and, more specifically, we will consider how AIB is meeting its targets and ensuring that there is a consistency of approach in dealing with distressed borrowers,'' Mr Lynch said.