Finance Minister Brian Lenihan has been accused of presiding over the most expensive bank bailout in the world as nationalised Anglo Irish Bank reported 8.2 billion euro.
The massive black hole for the first half of the year was twice as bad as experts predicted, prompting calls for the Government to pull the plug on the 23 billion euro survival plan.
Mr Lenihan said the final bill for saving Anglo would be known within weeks.
But Michael Noonan, Fine Gael finance spokesman, said six billion euro of taxpayers' money could be saved if an orderly wind-down was started now.
"Minister Lenihan must now give a definitive figure for the cost of saving Anglo Irish. Taxpayers have a right to know," he said.
Mr Lenihan said: "I can understand the anger and frustration which citizens have when they witness the scale of the losses in this institution but it must be understood that management and the board are working very hard as are the Government and EU authorities to bring certainty and finality to this problem."
Joan Burton, Labour Party finance spokeswoman, said: "The taxpayers were reassured at the time that this would be the cheapest bank bailout in the world. Instead it has turned out to be probably the most expensive," she said.
Anglo chairman Alan Dukes said the preferred plan inside the bank was to split it with 80% wound up and a new viable bank created from the remaining good quality loan assets.
The state-run bank, which has been funded by 23 billion euro of taxpayers' money, said it expects further losses as more troubled assets are shifted off the bank's books.
Anglo already holds the unenviable record for posting the largest losses in Irish corporate history last year, one of the biggest losses in world banking and now one of the worst half-year performances of any Irish company.