FBI and CIA agents have joined the hunt for those behind this week's suicide bombings in the Saudi Arabian capital of Riyadh.
A team of up to 60 members of the Federal Bureau of Investigation and the Central Intelligence Agency arrived in the kingdom to help the Saudi authorities.
The US State Department also warned Americans in Saudi Arabia of a report of a possible imminent attack targeted at the Red Sea port city of Jeddah.
Saudi Arabia admitted to security errors as US Attorney General Mr John Ashcroft said the bombings, which killed at least 34 people, made clear Saudi Arabia had a "terrorism problem" that it must address.