Coalition naval forces in the Persian Gulf have been deployed to counter possible terror threats against oil facilities in Saudi Arabia and Bahrain.
The British navy, which is part of an international task force that patrols in the Gulf, sent a statement on Friday asking merchant shippers to be on alert for suspicious vessels or activity.
Officials say the increased measures are in response to an al-Qaida threat last month against Gulf oil terminals. Authorities say oil exports in the region are proceeding as normal.
A U.S. State Department spokesman says the United States is ready to help if the Saudi government asks for assistance. The spokesman (Sean McCormack) refused to comment on specific anti-terror cooperation.
A U.S. Navy official in the Gulf Commander Kevin Aandahl told VOA that the United States supports the recommendation that commercial mariners be especially vigilant, and added that coalition forces in the Gulf are taking "prudent precautionary measures."
The stepped-up security includes enhanced vigilance at Saudi Arabia's Ras Tanura facility, the world's largest offshore oil loading terminal.