The USA has no plans for chip-and-pin technology
Current account customers of the Northern Rock have been stopped from using their debit cards in the US to buy items in stores.
The nationalised bank said it taken this measure to counter some apparent frauds on its debit cards there.
The current account holders can still use their debit cards in US cash machines, or anywhere else world-wide.
A bank spokesman said the fraud had affected "very few" people and the block on the cards was temporary.
"As a result of this potentially fraudulent activity we are temporarily blocking debit card transactions made in the US, or via a US merchant," he said.
"We have thus far only received a relatively small number of calls and have only made special arrangements for one customer," he added.
The banking industry body Apacs said the fact that the Northern rock had been hit by fraud in the US was not surprising.
The fraudulent use of credit and debit cards abroad has been booming at the same time as it has declined at home.
Card fraud abroad rose by 77% in 2007 to £207.6m, out of a total loss to fraud of £535.2m.
A spokeswoman from Apacs explained that it was happening especially in those countries which had not yet adopted chip-and-pin technology.
"Card fraud abroad has been the big growth area for the last two years," she said.
Northern Rock said the transactions appeared to involve cards that had been cloned rather than stolen.
The bank does not disclose how many current account holders it has, but it is thought to number in only the tens of thousands.
A few of the customers currently in the US have had their debit cards stopped completely and have been issued with replacements.
The Northern Rock first noticed the frauds in the last few days of last week.
The bank said any customers who had been affected would not be disadvantaged financially.