Hostilities continue to flare along the Sino-Vietnamese border with some of the heaviest fighting since China invaded Vietnam two years ago, but diplomatic analysts said today the possibility of a second major Chinese offensive seems unlikely.

Analysts said the recent clashes may have less to do with battlefield positions aloang the 500-mile border than with bargaining positions for upcoming conferences involving Cambodia and the noncommunist nations of Southeast Asia.

On the battlefield, China's official press reported today that Chinese border guards killed 85 Vietnamese soldiers in a four-hour battle after the Vietnamese had invaded a Chinese village yesterday morning and killed an undisclosed number of civilians.

The report also accused Vietnam of sending a reconnaissance plane into Chinese air space May 15 and killing or wounding more than 20 villagers in heavy shelling two days later that also destroyed rubber plantations, schools and homes.

In the war of words off the battlefield, Hanoi issued a news report today monitored in Bangkok accusing the Chinese of blaming Vietnam for the hostilities to divert public opinion from the recent intensified armed provocation against Vietnam."

The four-hour skirmish reported by Peking today aloang with two battles earlier this month, in which more than 250 Vietnamese soldiers are said to have died, are the largest reported clashes since China invaded Vietnam in February 1979 to teach it "some lessons."

Analysts said today, however, that there is little evidence that Peking is preparing for a second large attack. No major troop movements or supply shipments have been sighted along the border or the overland route leading to it, diplomats said.

The approaching rainy season in Southeast Asia and recent cuts in China's military budget also militate against possible attempts to teach Vietnam a second lesson, said analysts. The first war was considered costly in terms of deaths, resources and diplomatic prestige.

Although each side is reported to have about 250,000 soldiers stationed along the border, Western military experts believe Vietnam has a tactical advantage because of its access to sophisticated Soviet fighter planes. To offset that edge, they said, Peking would have to greatly augment its troop strength.

These analysts said the recent clashes may be intended to win propaganda points before the conference of the Association of Southeast Asian Nations in June and the international conference on Cambodia in July.

Some diplomats say Peking may be trying to portray Hanoi as a warmonger to harden views against it at the upcoming conference. Not only is Vietnam sporadically fighting China along their border, it also supports a pro-Vietnamese government in Cambodia that is battling Chinese-backed guerrillas.

Last week, Peking said Vietnam was trying to use the tension it was creating along the border to "fabricate the so-called China threat" and drive a wedge between the ASEAN countries and China, which jointly oppose Vietnam's role in Cambodia.

Laotian Foreign Minister Phoun Sipaseut completed a visit last week to three of the five ASEAN members -- Malaysia, Indonesia and the Philippines -- where he promoted a proposal pushed by Vietnam for a regional rather than worldwide conference on the Cambodian problem.

ASEAN, however, resolved Thursday that the U.N. Security Council members and seven Southeast Asian countries -- Cambodia, Vietnam and the five ASEAN members -- should participate in the July 13 conference to be held in New York. The other two ASEAN nations are Thailand and Singapore.

China, which supports the ASEAN stand on the international conference, may be trying to use reports of Vietnamese border violations to hold off the Laotians's diplomatic forays, according to diplomatic sources. It is easier to unite the nations against Vietnam if it behaves as an aggressor.

Other analysts speculate that the recent spate of fighting has more military than diplomatic reasoning behind it. By increasing pressure on the border, Peking may be attempting to keep Hanoi from shifting troops and equipment to Cambodiafor a blitz before the rainy season begins, they said.

Some of the fiercest fighting along the Sino-Vietnamese front took place early this month after Hanoi reportedly shifted 1,500 troops and several Soviet-built tanks to Cambodian areas close to the Thai border.

Vietnam for its part could be provoking border disputes to penalize Peking for aiding antigovernment guerrillas in Camabodia. In early May, China is said to have sent enough weapons and uniforms to outfit two battalions of noncommunist Cambodian guerrillas.