A bank in Northern Ireland hit by a massive robbery said on Friday it was considering the drastic measure of taking several denominations of notes out of circulation as a means of preventing the criminals enjoying their haul.
"All options are being considered," a source at the Northern Bank told reporters, requesting anonymity, following Monday night's audacious raid.
In the heist believed to be one of the biggest ever staged in Britain, more than ?22 million (US$42 million) was taken, all notes issued by the Northern Bank and in circulation exclusively in Northern Ireland.
Regular British notes issued by the Bank of England are also used in Northern Ireland, and could be used in place of the Northern Bank notes for the time being.
A bank spokesman said: "All Northern Bank notes will be honored by the bank. These will include any notes that are the proceeds of the robbery but which have been handled by ordinary members of the public in good faith."
The news came as police raided properties in Belfast on Friday in an attempt to recover the money, which officers believe might have been stolen by a gang linked to paramilitary forces.
Teams of uniformed officers searched for clues at several homes and commercial properties.
Gerry Adams, leader of the Catholic political party Sinn Fein, lodged a complaint with Britain's minister for Northern Ireland, Paul Murphy, to protest at the raids on Catholic homes.
The Belfast searches were "heavy-handed and aggressive" and intended to "further destabilize the political situation," he said.
Five officers carrying out the raids were injured in Belfast when their cars were attacked by up to 100 protesters throwing stones, bottles and other objects.
According to a Northern Ireland Treasury source, if Northern Bank's parent, the National Australian Bank group, decided against withdrawing the notes, the government might act instead.
Authorities in the British-ruled region might even pass legislation ordering the notes to be withdrawn from circulation, a treasury official told reporters, speaking anonymously.
Police have refused to rule out the possibility that a paramilitary gang was behind what officers described as a meticulously planned crime.
Elements linked both to Catholic groups such as Sinn Fein's armed wing, the Irish Republican Army, and to Protestant gangs are heavily involved in organized crime in Northern Ireland, despite the end of most sectarian violence since the 1998 Good Friday peace deal.
News agency reports in Britain on Thursday quoted a source close to the IRA as saying the group had nothing to do with the robbery, but these reports could not be independently confirmed.
The loot was snatched from the Northern Bank branch in downtown Belfast on Monday night, a day after two senior bank employees were taken hostage at their homes outside the city.
The gang, posing as policemen bringing news that a relative had been killed in a road accident, took over the homes of senior bank employees on the outskirts of Belfast last weekend.
The families were taken hostage elsewhere while the men, both senior bank managers, were ordered to go back to work on Monday and act as if nothing unusual was taking place.
At the close of business on Monday, they gave the thieves access to the bank's vault.