Paul Johnson, a contractor for US firm Lockheed Martin, was seized in Riyadh on 12 June. On 15 June, the group warned they would kill him within 72 hours if Al-Qaeda members in Saudi jails were not freed. It is not clear at what time on 18 June the deadline expires.

Johnson’s wife has pleaded for his release on Arabic TV, as Washington and Riyadh insisted they would not negotiate with the hostage-takers.

The US State Department again told its citizens remaining in Saudi Arabia to leave the country. The department reissued a travel warning on 17 June ‘to remind American citizens of the continuing serious threat to their safety while in Saudi Arabia’. It urged Americans planning to travel to Saudi to cancel their plans, and has already evacuated dependents and non-emergency workers at its embassy and consulates there.

There was credible information that extremists were planning further action against US and Western interests, the department said.