Cambodian Troops Seize Guerrilla Base : Civil War: The stronghold is lost hours before rebel leader Prince Norodom Sihanouk returns from exile.

Cambodian government troops Friday captured a strategic guerrilla stronghold after four days of fierce fighting in the first major victory of the Communist government’s counteroffensive, Phnom Penh Radio reported.

Hours later, guerrilla leader Prince Norodom Sihanouk returned home from exile.

The army was in full control of Svay Chek, a cluster of villages in northwest Cambodia that had been in the hands of the Khmer People’s National Liberation Front since early December, according to the radio. The front is one of three guerrilla factions fighting the Vietnamese-installed government.

Gen. Dien Del, the front’s deputy commander, charged that Vietnamese troops were involved in the attack, although Vietnam said that it withdrew all its troops in September after 11 years of occupation.

The New York Times on Friday quoted Eastern European diplomats as saying several thousand Vietnamese troops and military advisers returned to Cambodia in October to help government troops defend Battambang and Sisophon, two important cities.

The newspaper’s report from Phnom Penh quoted the diplomats, who were not identified, as saying that about 5,000 Vietnamese soldiers are still in Cambodia.

Dien Del, interviewed in the key Thai border town of Aranyaprathet, said Svay Chek was heavily shelled by tanks and Soviet-made, multiple-rocket launchers during the final assault. He also said the 600 guerrillas defending the town fled in confusion after they failed to receive word that a front-line position had fallen earlier. There were no reports of casualties.

The action comes three days before peace talks are to begin in Indonesia between the Phnom Penh government and the three guerrilla groups led by Prince Norodom Sihanouk.

Sihanouk, once Cambodia’s ruler, returned Friday from 11 years of exile to live in a “liberated zone” in Oddar Meanchey province until his entire country is free.

Armed guerrillas and civilians chanted “Long live his royal highness!” as the prince’s party crossed by car from Thailand into the northwest province.

Sihanouk told about 100 reporters bused in for the homecoming: “All Cambodians want to live in Cambodia and die in Cambodia. I am 68 years old and I feel more and more I could die on foreign soil, even if it is friendly foreign soil like China or North Korea.”

With him were his wife, Monique, and their platinum-white poodle, Mickey.

Sihanouk, who went into exile after the Vietnamese invasion in December, 1978, has lived in palaces and luxury hotels in China, North Korea, Thailand, France and other countries that support his guerrilla movement and have provided him with a comfortable life.