LONDON,(Reuters) – Coalition naval forces are helping to guard vital oil installations in the Gulf as part of heightened security following an Al Qaeda threat last month, naval sources said on Friday.

In their sights are Saudi Arabia’s Ras Tanura terminal, the world’s biggest offshore oil export facility, and Bahrain’s Bapco refinery.

“Acting on information received, Coalition naval forces, operating in support of Saudi and Bahraini forces have deployed units to counter a possible maritime threat to the oil facilities at Ras Tanura,” Britain’s Royal Navy in Dubai said in a statement.

Saudi Arabia’s own security forces and navy are guarding facilities in the world’s biggest oil exporter and coalition forces are patrolling only in international waters.

“Coalition forces are taking the prudent, precautionary measures and focusing on maritime security operations in the Gulf on these possible threats,” said Kevin Aandahl, spokesman for the U.S. Naval Forces Central Command in Bahrain.

“We’re constantly and routinely conducting maritime security operations in the Gulf and international waters and these operations deny terrorists the use of the maritime environment as a venue for attack.”

A Saudi security adviser also said any operations in the Gulf were entirely routine and added there had been no further threat since Al-Qaeda on Sept. 11 said it would target economic interests in the Gulf.

“This is part of the on-going exercises between the U.S., British, Bahraini and Kuwaiti forces… in the Gulf,” said Nawaf Obaid.

Oil prices initially rose about 30 cents to around $61 as traders recalled a foiled attack in February on Saudi Arabia’s huge Abqaiq facility, the world’s biggest oil processing plant. Prices later eased.

Crude oil shipments were continuing as normal from the kingdom’s main east coast terminal, industry sources said.

Riyadh is exporting around 7 million barrels per day (bpd) of oil to world markets, with Ras Tanura handling most of it. The terminal has the capacity to export 6 million bpd.

It was unclear how much oil the terminal was exporting on Friday and national oil company Saudi Aramco declined to make any comment.

In an interview with Reuters in July, Vice Admiral Patrick M. Walsh, who is in charge of U.S. Naval Forces Central Command, said he was concerned that al Qaeda might attack oil facilities from the sea. He said the unsuccessful attack on the Abqaiq oil facility had made him especially wary. “When I look at that, my first reaction is that they (al Qaeda) are going to turn to the sea. I recognise that when they are thwarted in one direction they turn to another.”