Earlier, there were reports that Bahrain had called in forces from neighboring states to put down the protests that began on Feb. 14.

The Bahraini opposition groups including the largest party Wefaq said on Monday that any intervention by foreign forces on the Gulf island will be seen as a declaration of war and occupation.

Hundreds of cars were parked at the Saudi side of the bridge with many expatriates, mostly Westerners, wanting to get across.

Craig Elison, who works for a multinational company in Jubail but stays with his family in Manama, said: "I've been stranded near the bridge since 3 p.m. today. I don't know what is happening. All I can see is a fleet of military convoy going across the bridge.”

Craig said he spoke to one of the officials on the bridge, who said it would reopen once the military convoy passes.

There are anxious people on the Saudi side of the bridge who have families living in Bahrain.

John Roy, who works in Bahrain and is on a visit to Saudi Arabia, said: "I came in the morning over the bridge and there was no problem. Of course, the number of people commuting on this bridge has dropped significantly since the trouble began in Bahrain three weeks ago."

Roy, who works for a multinational company, added that if the bridge does not reopen then he would lodge in one of the hotels. He was making frantic calls to his wife in Manama and was assuring her that he will be home soon.

People have been regularly commuting between the two countries despite the trouble in Bahrain, but today is the first time the bridge has been closed.