U.S. Marines took full control Friday of the strategic port of Umm Qasr in southern Iraq, and thousands of Marines and British soldiers dug in around the city.

Few civilians were visible in the center of the city of 45,000, but lights were on in apartment buildings.

Adm. Michael Boyce, chief of the British defense staff, told reporters in London the Marines were in full control of Umm Qasr (pronounced oom-KAHSR').

"Umm Qasr has been overwhelmed by the U.S. Marines and now is in coalition hands," Boyce said. "This port is a vital objective. ... It's going to become one of our main ways of getting humanitarian aid, hopefully within days ... into Iraq."

At the Pentagon, Air Force Gen. Richard Myers, chairman of the Joint Chiefs of Staff, confirmed Umm Qasr's capture.

British minesweepers must clear a safe sea route to Umm Qasr before cargo ships can enter the port, Boyce said.

Located along the Kuwait border, Umm Qasr will be useful for moving military supplies into Iraq and control of the city will likely speed the clearing of Iraqi resistance in the south. Parts of the city, located 290 miles southeast of Baghdad, was given to Kuwait under agreements the United Nations brokered after the 1991 Gulf War.

Boyce also said U.S. and British forces were on the outskirts of Basra, southern Iraq's largest city.

The ground attack on Umm Qasr followed a night of intense shelling by U.S. and British forces in the area.

After night fell Friday, American forces set off flares above the airport, port and former U.N. installations, apparently to light the area so they could see whether there was any activity. All appeared quiet, although machine gun fire was audible in the distance.

Soldiers rested on Humvees and tanks in the desert outside the city and seemed in good spirits. Some asked journalists to send greetings to their families at home.

Australian forces intercepted one Iraqi patrol boat loaded with about 60 sea mines and other military equipment in the area of Khawr Abd Allah, a stretch of water in the approach to Umm Qasr, Australian officials said. In all, Myers said, coalition forces boarded three Iraqi tug boats and a total of 130 mines were discovered.

Brig. Maurie McNarn, commander of the 2,000 Australian troops in the Persian Gulf, said a coalition flotilla of rigid-hulled inflatable boats intercepted the Iraqi tug.

"That's a good save, a real good save in terms of the coalition," he said.

British, Australian and American ships also were transporting U.S. Marines, he said.

U.S. Marines took several hundred prisoners, who a U.S. military official said were draftees in very poor condition rather than "top-notch Republican Guard types."

"A lot of them looked hungry," the official said, speaking on condition of anonymity. "They haven't been fed in a while."

He said they fought with small arms, pistols, machine guns and rocket-propelled grenades.

Boyce said British forces in the area were dealing with hundreds of Iraqi prisoners, but added he did not know how many had surrendered and how many had been taken prisoner.

British officials also said the oil infrastructure at Umm Qasr was not destroyed by Iraqi troops.

"Any attempt by Saddam Hussein to release oil into the Gulf and create an environmental disaster has been thwarted," British Defense Secretary Geoff Hoon said.

"It is not just a matter of protecting the oil fields from sabotage, but more widely to ensure that to the greatest extent possible, the civilian infrastructure of Iraq remains intact."

Boyce said he had no information about the situation in oil fields near Baghdad, the capital.

"We are absolutely determined not to allow Saddam to (cause) yet more damage to the lives of his people through some sort of scorched-earth policy," Boyce said.