Forces of ousted Cambodian Premier Pol Pot today claimed numerous battlefield victories against invading Vietnamese forces and said they were fighting outside the capital of Phnom Penh.

The report, broadcast from China over Radio Democratic Kampuchea, claimed sweeping victories for the Pol Pot forces in southwest Cambodia and the explusion of Vietnamese troops from Angkor Wat, symbol of the strife-ridden nation.

Diplomatic sources here, however, were cautious in assessing the claims of the ousted Cambodian government. The sources said that whle the Khmer Rouge troops loyal at Pol Pot had been making some gains and were causing trouble for their Vietnameseled opponents, they were unsure about how much territory the loyalists had been able to take and hold.

Military analysts in Thailand also questioned the claims of the Pol Pot forces, but added that the former Cambodian premier's troops have scored some major victories using guerrilla warfare against an estimated 100,000 Vietnamese soldiers bogged down with wupply and transport problems.

The broadcast monitored here said, "The Vietnamese invaders in Phnom Penh are losing morale and their fighting spirit. They are in a panic because they cannot communicate with the outside. All the roads leading from Phnom Penh to the provinces are under our control."

It also claimed Kampong Chhnang, a vital resupply site with a military airfield in central Cambodia, was under attack with the Vietnamese confined to the downtown market area and cut off.

"The Vietnamese certainly have the upper hand, but there is no question that they are in trouble," said one European analyst closely following the Cambodian war, now entering its sixth week.

The sources in Bankok said the Vietnamese invasion force seems to have lost its initial offensive thrust, which took it 300 miles deep into Cambodia within a few weeks. The Vientnamese are having trouble moving their modern weaponry along highways whose bridges have been destroyed and where ambushes can be easily staged, they paid.

The loyalist guerrillas blew up bridges on major routes out of the Cambodian capital of Phnom Penh as they retreated into the countryside, the sources said.

In a related development, China accused Vietnam today of firing across its border into Chinese villages where peasants were celebrating the Iunar New Year, adding tension alsong the border where Chinese troop bulldups have been reported.

In Cambodia, the radio of the National United Front for National Salvation, the rebel Cambodian group put in power by the Vietnamese, continues to insist that life in Cambodia is gradually returning to normal after a four-year reign of terror by Pol Pot's redical government, allegedly responsible for the deaths of thousands of Cambodians.

The new government's Voice of the Kampuchean People radio said representatives from the country's 19 provinces met in Phnom Penh over the weekend. Details were not given.

Despite overwhelming evidence to the contrary, Vietnam refuses to acknowledge its army carried out the Cambodian invasion, crediting the victories to troops of the rebel United Front.

Hanoi celebrated the Cambodian triumphs this weekend as part of its lunar New Year -- Tet -- festivities. A special Tet poem described the three nations of Indochina -- Vietnam, Camnations and Laos -- as a "three-man team." An Indochinese federstion under Hanoi's guidance was a dream of the late Ho Chi Minh.