The alert has been issued from the British and American embassies in the kingdom.

“We continue to receive information that terrorists may be considering further attacks against Western targets in Saudi Arabia, including housing compounds,” the British embassy said, according to Sky News.

Recent successes by Saudi security forces may have stemmed some strikes, but foreigners remain at risk from opportunistic attack, the embassy said.

The US embassy in Riyadh told its citizens the State Department allowed their return, but cautioned  of  "remaining security concerns."

Raids

Security in the kingdom was stepped up after a triple suicide attack on western compounds by militants linked to Osama bin Laden’s al Qaeda killed 35 people in May.

Saudi security forces have arrested more than 150 suspected militants, killed several others and uncovered substantial arms and ammunition stores.

Last week police in the kingdom seized 6 suspected militants, foiling attacks planned against key installations, the interior ministry said.

Rocket-propelled grenades, 72 kilograms of explosives, detonators, and more than 20 tons of chemicals used to make explosives and rifles, were found during the raid.