ALLIED Irish Banks (AIB) is to review all its procedures for detecting fake notes, including re assessing its technology, following a complaint that a customer was sold forged $100 bills.

An AIB spokesman said yesterday that the bank was very concerned about the matter and would be reviewing all its procedures, including staff training and screening of foreign currencies.

It is understood that a customer purchased $100 bills in a Dublin branch, before a recent trip to the US. When he tried to pay for goods using one of the bills, the bill was found to be a forgery.

The AIB spokesman said all foreign currency notes are screened before being passed on to customers and are bought from the bank's own reputable sources. He said it was "quite an unusual occurrence", given the number of foreign currency transactions carried out by its Irish branches every year.

Although the spokesman admitted that there had been several incidents where customers have claimed that foreign notes they purchased in Ireland were forgeries, he was unable to specify an exact number.

The spokesman declined to comment on the specific case, which involved a tax appeals commissioner who is said to have been publicly embarrassed when a $100 bill he was using to purchase a pair of shoes in New York, was refused, because it was a forgery.

The AIB customer, Mr John O'Callaghan, could not be contacted yesterday.

A spokesman for the Central Bank said it had no legal role in the detection of foreign currency forgeries. "If forgeries are emerging, the information is usually passed through the commercial bank network," he said. "However, we would pass on information, regarding forgeries, if we thought the commercial banks did not have this information already.

The AIB spokesman said the commercial banks regularly swoop information on forged currencies, through their various federations.

Banking sources say there are particular difficulties with US dollars. It is one of the most commonly forged currencies because it is the most commonly used currency internationally.

It is understood that there are some extremely high quality dollar forgeries in circulation, which are very difficult for the public to spot. It has been claimed that some Middle Eastern governments are printing high quality $100 bills.

The US government is introducing a new $100 bill to try to foil counterfeiters.

The AIB spokesman said any customers who had doubts about foreign currencies they had received should contact their local branch.