Allied Irish Banks (AIB) has announced plans to cut more than 2,000 jobs in 2011 and 2012, in order to lower costs.
The news came as the bank revealed it made a total loss for 2010 of 10.2bn euros (£9bn), compared with a loss of 2.3bn euros in 2009.
This included a loss of 7bn euros on the transfer of assets to Nama, the government's asset management agency.
AIB received a 3.5bn-euro bail-out from the Irish government in 2009 and is now majority owned by the government.
AIB is to be merged with building society EBS as part of government plans to reduce the number of banks in the country.
The merger is intended to form one of two new strong universal pillar banks in the Irish Republic, along with Bank of Ireland.
AIB said the reduction of staff would take place on a "phased basis".
It said that business and market conditions remained challenging, adding that it would sell some non-core assets and wind down others.