Cambodian and Vietnamese officials conducted a ceremony here yesterday symbolizing Vietnam's announced intention to withdraw about 10,000 troops from Cambodia.

Launching the pullout with fanfare for the benefit of 37 Western reporters admitted to Cambodia for the occasion, the Vietnamese paraded a dozen tanks, 15 artillery pieces and 57 trucks carrying perhaps 1,000 soldiers through Phnom Penh.

Cambodian orphans, said to have lost their parents during the Communist Khmer Rouge's 1975-78 reign of terror, performed a traditional dance in front of the towering Alangkar temple.

The reporters' two-day program also included a news conference, presentation of medals, the loading of the tanks onto barges for the trip down the Mekong River to Ho Chi Minh City (Saigon), and a helicopter ride to watch the first column of troop trucks and artillery cross the border into Vietnam's Tay Ninh province.

Western reporters were told that more than 10,000 of the estimated 180,000 Vietnamese troops in Cambodia would be withdrawn to Vietnam during May.

In Bangkok, Thai Foreign Minister Siddhi Savetsila told reporters: "The withdrawal has no meaning. We want a total withdrawal. These troops might be sent right back. Who knows?"

In Washington, State Department spokesman Alan Romberg said a similar announcement of a withdrawal last year resulted in little more than troop rotation, "so we have to wait and see what this really means."