A U.S. lawmaker says Irish Republican political leader Gerry Adams was detained at Washington's National airport Friday.

Democratic Congressman Brian Higgins of the state of New York says Adams was detained at a security checkpoint before he was scheduled to catch a flight to the city of Buffalo, where he was to appear with Higgins at a St. Patrick's Day event. 

Higgins says Adams was detained, because he was on a terror watch list, causing Adams to undergo a lengthy inspection. 

Adams is the leader of Sinn Fein, a political party allied with the Irish Republican Army, which has been engaged in a decades-long struggle to end British rule in Northern Ireland.

He had appeared at a St. Patrick's Day event at the White House earlier Friday with Irish Prime Minister Bertie Ahern and other Irish leaders.

Some information for this report was provided by AP and Reuters.