UPDATE 1-Saudi Qaeda tape says shows killing of American

BC-SECURITY-SAUDI-VIDEO (UPDATE 1)

UPDATE 1-Saudi Qaeda tape says shows killing of American

(Adds details, background)

DUBAI, June 13 (Reuters) - A purported al Qaeda videotape posted on an Islamist website on Sunday claims to show the killing of a U.S. employee in the Saudi capital Riyadh last week.

"The murder of the Jewish American Robert Jacob, who worked for the Vinnell espionage firm," a statement announcing the video on the Website says.

The video shows a man, whose face cannot be seen but who seems to be a Westerner, fall to the ground in front of a garage as two men holding guns run towards him. The statement is signed "the voice of Jihad: al Qaeda in the Arabian Peninsula."

U.S. national Robert Jacobs was killed by gunmen on Tuesday in the fifth assault on Westerners in the world's leading oil exporting country in five weeks.

He worked for U.S. defence contracting firm Vinnell, a unit of Northrop Grumman (NOC.N) Corp which trains the Saudi National Guard, an elite force protecting the pro-U.S. monarchy.

Saudi-born Osama bin Laden's al Qaeda, blamed for the September 2001 attacks on U.S cities, has vowed that 2004 would be "bloody and miserable" for Saudi Arabia, a key U.S. ally.

The Gulf state, the birthplace of Islam, has been fighting militants for a year, arresting and killing many, including eight on a wanted list of 26 militants. Riyadh says the militants are going for soft targets after the clampdown.

Reut19:53 06-12-04