London ? A day after announcing the guarantee of bank deposits for two years, the Irish government on Wednesday said it may demand stock from any bank that needs its assistance.

“The Minister may subscribe for shares and other securities in a credit institution on such terms as he sees fit,” the government said in a summary posted on the Irish parliament Web site.

The move comes as the estimated $566 billion guarantee was a huge success, in its initial stages at least.

The stock prices of Allied Irish Banks, Bank of Ireland, Anglo Irish Bank and Irish Life and Permanent have rallied since the announcement, and media reports suggested that British customers and corporations have flooded Irish institutions with deposits.

Prior to the government’s announcement, Irish banking shares had been under tremendous pressure due to their exposure to wholesale funding as well as the downturn of the local economy, the first in Europe to officially be in a recession.

Recent disclosures have shown that top hedge fund managers like Tiger Global Management and the Citadel Investment had been shorting Irish banks prior to a short-sale ban.

It’s also infuriated the British, for several reasons. The Irish are not backing the deposits of U.K. banks that operate in Ireland, like HBOS or the Royal Bank of Scotland.

It’s also putting pressure on the U.K. government ahead of a statement on Monday by Chancellor Alistair Darling on bank guarantees.

Prime Minister Gordon Brown suggested the U.K. won’t go the Irish route in an interview with the BBC.

“Let’s remember, the Irish are dealing with taxpayers’ money here,” Brown said. “We have got to get what’s right and also what’s reasonable and of course we look at every intervention that is necessary to take but I think people can see from our actions so far that depositors have been protected.”

But the market cost for insurance would overwhelm Irish banks.

Based on credit-default swaps trading over three months, Collins Stewart analyst Alex Potter calculated the guarantee would have wiped out the profits of any of the Irish banks, save for AIB, which would have seen 67 percent of its pretax profit wiped out.

Ireland also may find it more expensive to raise cash. The cost of insuring Ireland’s sovereign bonds against a default more than doubled on Tuesday.

At about $129,000 per citizen, the Irish taxpayer will be stuck paying the tab for a generation if banks were to actually need the government cash on offer.