China accused Vietnam of preparing for war against Thailand, while Vietnam accused China of preparing to launch an new attack by massing 300,000 troops on their common border, as the 10th session of peace talks between the two countries ended today in deadlock.

Both sides said the latest negotiationg session resulted in no progress, but they agreed to meet again in Peking at an unspecified date.

China's chief negotiator, Han Nianlong, accused the Vietnamese of turning Cambodia and Laos into bases for "threatening, subverting and invading Southeast Asian countries." He repeated the Chinese demand that the Vietnamese pull out of Laos and Cambodia.

The chief Vietnamese negotiator, Vice Foreign Minister Ding Nho Liem, charged that China has 30 divisions posied for a renewal of fighting with Hanoi. The peace talks began after a 29-day war between the two countries ended March 17.

Lieu accused China of trying to aggravate the border tension in an attempt to exert pressure at the talks and create the pretext for a renewed war against Vietnam.

"Coupled with these dangerous armed provocations is the stepping up of collusion with U.S. imperialism . . ." as some Chinese leaders look for support "to launch another aggressive war against Vietnam," he charged.

The Chinse negotiator accused the Vietnamese of encouraging and financing secret Thai opposition organizations and armed groups based in Laos. He charged that Vietnam was stationing heavily armed troops on the Cambodia-Thailand border in preparation for a war against Thailand.

Both sides issued statements accusing each other of border provocations and violations during the past month.

Diplomatic sources siad neither side want to be the one to call off the deadlocked talks, but they simply may allow the negotiations to lapse with a vague understanding that they could be resumed later.

At a news conference after the session, the Vietnamese negotiator said mass graves had been found recently in Cambodia.

"Among the bones of the dead bodies were many instruments to massacre people which had the marks 'made in China,'" he charged, without elaborating.