China has admitted for the first time that it sent more than 300,000 combat troops to Vietnam to fight against U.S. forces and their South Vietnamese allies.

Th semiofficial China News Service said Tuesday in a report monitored in Hong Kong that China sent 320,000 soldiers to Vietnam during the 1960s. It also spent over $20 billion to support Hanoi's regular North Vietnamese Army and Viet Cong guerrilla units.The agency report cited "The History of the People's Republic of China," published by the official State Archives Publishing House, as saying that more than 4,000 Chinese soldiers were killed in the war.

Fighting finally ended when victorious North Vietnamese tanks battered their way into the grounds of Doc Lap Palace in Saigon on April 30, 1975.

During the war China repeatedly denied U.S. allegations that its soldiers were operating in Vietnam.

U.S. intelligence reports at the time spoke of U.S. combat units finding soldiers dressed in Chinese combat gear and wearing Chinese insignia.

During the 10 years of direct U.S. involvement American troop levels reached over 500,000. Estimates of North Vietnamese Army units varied, but Hanoi maintained throughout the war its soldiers went only as volunteers to help the southern Viet Cong guerrilla movement.

Units from South Korea, Australia and New Zealand fought alongside U.S. and South Vietnamese soldiers, with logistical support from Thailand and the Philippines.

Both presidents Lyndon Johnson and Richard Nixon were extremely wary of allowing U.S. aircraft to bomb too close to the Chinese border with North Vietnam for fear of involving the Chinese on a larger scale.

But pressure groups seeking news on Americans listed as missing-in-action in Indochina say a small handful of U.S. pilots bailed out over Chinese territory after their planes were hit by Vietnamese ground fire.