Anglo Irish Bank was nationalised in January
The Irish government has announced that it will inject 4bn euros ($5.6bn; £3.5bn) into Anglo Irish Bank after the lender reported big half yearly losses.
For the six months to the end of March, the bank made a pre-tax loss of 4.1bn euros due to losses on property loans.
The country's finance minister, Brian Lenehan, described the losses as "extremely disappointing".
Anglo Irish was nationalised in January amid fears it would collapse after a series of controversial transactions.
The bank made a profit of 667m euros in the same period a year earlier.
"It is important to remember that this is the first time that we have put money into Anglo Irish Bank," said Mr Lenihan.
He said the bail-out was needed to protect the wider economy in the event of the bank's failure.
The Irish government needs to gain EU approval before it can hand over the money.
"The minister's decisions place the bank on a sound financial footing and we are determined to repay the taxpayer by creating a viable, efficient and respected bank," said Donal O'Connor, Anglo Irish's executive chairman.
In December last year, the bank's chairman, Sean Fitzpatrick, resigned after admitting that he had concealed millions of euros in personal loans from the Dublin-based bank.
Mr Fitzpatrick hid the loans from shareholders by temporarily transferring them to another bank before each year-end to avoid revealing them in the accounts.