Vietnam is threatening to cancel its appearance at talks to end the 9-year-old war in Cambodia because a communique issued by a group of Southeast Asian nations expressed strong support for Cambodian rebels.

Vietnam's Foreign Ministry on Thursday issued a statement saying the joint comminuque issued by the ministers of the Association of Southeast Asian Nations, or ASEAN, had undermined the talks, scheduled for July 25 in the Indonesian capital of Jakarta.The statement said "such a hostile communique released by the ASEAN countries heralds their negative stance" at the talks. With such a stance, the talks "will not bring about expected results," it said.

The statement was carried by the official Vietnam News Agency, monitored Friday in Bangkok.

On Thursday, the foreign ministers of Vietnam and Laos issued a joint statement criticizing the association's stand on the Cambodian issue. That statement said: "The continued adherence to that stand . . . will contribute to the discontinuation of the informal meeting in Jakarta."

The controversy is over a communique issued Tuesday by ASEAN, whose members include Thailand, Malaysia, Indonesia, the Philippines, Singapore and Brunei.

The communique, issued after a two-day conference among group members, expressed strong support for the guerrilla groups fighting Vietnamese forces that invaded Cambodia in late 1978.

It called Vietnam's occupation of Cambodia a threat to regional security and urged the world community to deny Vietnam any aid that may help prolong its occupation.