AIB has said the amount of money on deposit at the bank has fallen by €13bn since the start of the year.
The figure came in a trading update issued by the bank this afternoon.
The bank said the reduction was mainly due to an outflow of money from companies and financial institutions.
AIB said funding conditions for the bank in recent months had been increasingly tough, and as a result it had received a range of funding from central banks.
It said profits in all of its businesses - excluding loan losses - were lower compared with last year.
AIB said the percentage of its mortgage customers in arrears continued to rise in the three months to the end of September, though not as quickly as in the second quarter.
Of its owner-occupier mortgages, 2.6% are in arrears for more than 90 days compared with 2.1% at the end of June.
It said future changes in these figures would be strongly influenced by the rate of unemployment.
The bank said the number of loans in danger of not being re-paid, known as 'criticised' loans, increased again in the third quarter of this year, especially in Ireland, as the property market remained weak.
One factor in the increase is €4.4bn of loans that will not now be transferred to the National Asset Management Agency.
The Central Bank has estimated that losses on these will be 56%.