Catalino Lucas Diaz, from Florida, was charged with unlawful entry, threatening with a bomb and throwing a missile following the incident in Washington on Friday while Ahern was meeting George Bush.

Diaz is alleged to have scaled a security fence with three packages and was on his way towards the main White House building when he was spotted by Secret Service agents.

He is said to have told the security men that he had a bomb but was bundled to the ground and arrested before he could detonate the supposed device.

Agents used a water cannon to destroy the three suspicious packages, which were later found to be a book, a tape recorder and some other items.

The incident occurred as Bush was meeting with Bertie Ahern and foreign affairs minister Dermot Ahern at around 3.30pm Irish time on Friday.

The politicians only learned of the incident as they were leaving the meeting.

A press conference due to be held within the White House was cancelled and went ahead in the Old Executive Office building across the street on Pennsylvania Avenue after Bush personally intervened, telling the Secret Service to "make it happen".

The White House was locked down for more than three hours after the incident and the daily press briefing was delayed as a result.