BEIRUT, Lebanon — U.N. investigators have asked the Syrian government to let them question the president and foreign minister about the assassination of a former Lebanese leader, a spokeswoman for the probe said today.

Nasra Hassan, who speaks for a U.N. commission heading the inquiry, also said investigators want to interview former Syrian Vice President Abdul-Halim Khaddam "as soon as possible."

Khaddam alleged in a television interview broadcast Friday from Paris that the Syrian president had threatened former Lebanese Prime Minister Rafik Hariri several months before Hariri was assassinated in a Feb. 14 truck bombing.

"The U.N. commission has already sent a request to interview Syrian President Bashar Assad and Foreign Minister Farouk al-Sharaa, among others," Hassan told The Associated Press.

"The commission is waiting for a response from the Syrians," she said. She refused to say when the request was made.

There was no immediate Syrian government comment on the request, the second time investigators have asked to meet with the president. The first time was in July and Syrian officials refused.

The commission has said several people whom Hariri spoke to after he met Assad in August 2004 said he told them the Syrian leader had threatened him over his opposition to extending the term of Lebanon's pro-Syrian president.

Syrian officials, including Foreign Minister Farouk al-Sharaa, have denied any threat was made.

But after Khaddam's interview, Syria's ruling Baath Party stripped him of membership and joined parliament in demanding his trial on a charge of high treason, the official news agency SANA reported Sunday.

While Khaddam, who is in France writing a book, said Friday that he ultimately planned to return to Syria with his family, it was unclear if he would go back facing a treason charge. Conviction would bring the death penalty.

In two interim reports published late last year, the commission accused Syrian and Lebanese intelligence officials of being involved in the killing of Hariri. In an interview with the media, the outgoing commission chairman, Detlev Mehlis, has said Syrian "authorities were behind the assassination."