The high command of Al Qaeda appear to be behind terror threats to oil facilities in Saudi Arabia and Bahrain, a U.S. official said Friday.

"Indications are that Al Qaeda central — Usama bin Laden or his second in command Ayman al-Zawahiri — as well an Al Qaeda affiliate" are involved in the plot, the U.S. official told FOX News on the condition of anonymity.

That's significant, the source said, because the last time one of Al Qaeda's top two were believed to have had a hand in an operation was London's foiled airline bombing plot last August.

Several sources have said fairly specific information had been intercepted that indicated the attack would come soon in the area of eastern Saudi Arabia.

Coalition naval forces in the Gulf were on a heightened state of alert over possible terror threats to oil facilities in Saudi Arabia and Bahrain, Western naval officials said Friday.

A British navy official, speaking on condition of anonymity because he was not authorized to speak to the press, said a threat from Al Qaeda to target Gulf oil terminals had resulted in stepped-up security and vigilance at Saudi Arabia's Ras Tanura terminal, as well as a refinery in Bahrain.

Oil exports in the region were proceeding as normal, he said.

Click here to go to FOXNews.com's Mideast Center.

The British navy, part of the Italian-led Coalition Task Force 152 that patrols international waters off the Ras Tanura terminal, sent an e-mail warning on Friday asking merchant shippers in the region of Bahrain and eastern Saudi Arabia to be on alert for suspicious vessels or other activity.

Task Force 152 also contains ships from French, U.S., German and other navies.

The U.S. Navy's 5th Fleet, headquartered in Bahrain, said it was aware of the British warning.

"We support the recommendation that commercial mariners be especially vigilant while transiting the Gulf," Lt. Cmdr. Charles Brown said Friday in a statement e-mailed to The Associated Press.

Brown acknowledged the security measures but referred to them as "routine."

"Coalition forces are taking prudent, precautionary measures and focusing maritime security operations in the Gulf on these possible (Al Qaeda) threats," he said.

"These operations are nothing new. Coalition maritime forces routinely conduct maritime security operations in the Gulf," he added.

The British official said the coalition ships were confining their patrols to international waters and had not been invited by Saudi Arabia to patrol inside its territorial waters near the terminal.

"The Saudis are very protective of their patch," the British official in Dubai said, describing the patrols as normal naval operations that had been under way since 2002, albeit on a heightened state for the past month.

Ras Tanura, just north of the Saudi oil capital of Dhahran, is the world's largest offshore oil loading facility with a capacity of 6 million barrels per day. Bahrain, an independent island kingdom, lies in the Gulf just off the Saudi east coast.

In February, Al Qaeda-linked car bombers attacked the Abqaiq oil processing plant near Dammam, Saudi Arabia, killing two guards. The attack did no damage to the facility, but sent oil prices briefly spiking up $2 a barrel.

On Friday, light sweet crude for December delivery fell 10 cents to $60.26 a barrel.

Catherine Herridge and the Associated Press contributed to this report.

Click here to go to FOXNews.com's Mideast Center.