U.S. Marines are in full control of the strategic port of Umm Qasr in southern Iraq, a British military official said Friday.

"Umm Qasr has been overwhelmed by the U.S. Marines and now is in coalition hands," Adm. Michael Boyce, chief of the British defense staff, said in London.

British forces in the area were dealing with "significant numbers" of Iraqi troops who had surrendered, Boyce said, but he could not be more specific.

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

Umm Qasr, located along the Kuwait border about 290 miles southeast of Baghdad, would give U.S. and British forces access to a port for military and humanitarian supplies and speed the clearing of Iraqi resistance in the south.

Once British minesweepers finished clearing a safe sea route to Umm Qasr, it would become "one of our main ways" to get humanitarian aid into Iraq, Boyce said.

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

Australian forces intercepted an Iraqi patrol boat filled with sea mines and other military equipment in the area of Khawr Abd Allah, a stretch of water in the approach to Umm Qasr, a spokeswoman for British forces in the Gulf said.

A U.S. military official said on condition of anonymity, "We do have a big presence at this time."

The Marines also took several hundred prisoners, who were described as being draftees in very poor condition rather than "top-notch Republican Guard types."

"I kind of felt sorry for them," the American official said. "A lot of them looked hungry. They haven't been fed in a while."

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

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," 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.

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