The U.S. embassy in Saudi Arabia said it had suspended consular services in the kingdom for two days due to "heightened security concerns", after warning of threats against Western oil workers.All services in Riyadh and at the consulates in Jeddah and Dhahran have been cancelled for Sunday and Monday, it said in a statement posted on its website Saturday. The embassy warned U.S. citizens to take extra precautions and keep a low profile if they were out in public.