"Travellers found in the Green Channel with goods in excess of their allowances risk having the goods seized and they may also be subject to prosecution, " said a spokeswoman for the Revenue Commissioners. "It is important that people make themselves aware of the regulations before they go on their trip."

The Aer Lingus seat sale, which ended on Thursday, included flights to Boston, New York, Washington, Chicago and Los Angeles.

Radio, television and newspaper ads emphasised the good value of shopping in the States and prospective passengers were told they could take three suitcases with them "to ensure you don't leave any bargains behind."

However, passengers currently may not bring home purchases in excess of 175 without declaring themselves to customs and paying the required duties. Despite this, of an estimated 25m spent in 2005 on pre-Christmas shopping trips just 42,141.30 was collected in customs duty and tax.

Presumably, passengers taking advantage of the Aer Lingus deal are confident that their excess goods will not be picked up by customs and Aer Lingus said it would not be making any comment on the matter. With the euro at an all-time high against the dollar, shopping trips to America have never been more popular.

However, according to the Revenue, people planning to spend big bucks Stateside should be careful. "The best advice we can give is for people to check their allowances before they go, declare anything over the limit when they come back and if they're in any doubt enter the Red Channel, " said the spokeswoman.