In the first visible dissent from Secretary of State Alexander M. Haig Jr.'s hard line against Vietnam, New Zealand Foreign Minister Brian Talboys has warned against tactics that "might push the Vietnamese into the arms of the Soviet Union."

Talboys delivered his cautionary words to Haig in private during a session of the foreign minister meeting of the ANZUS (Australia-New Zealand-United States) alliance here, and subsequently spoke of it in a press conference.

In a final communique and talks with reporters today, all three foreign ministers backed the current political initivatives on Vietnam taken by the noncommunist states of Southeast Asia, especially Thailand. But U.S. sources conceded that there is no agreement in ANZUS about a Vietnam policy for the longer run.

Haig, in earlier discussions during his current Asian tour, has treated Vietnam as a virtual satellite and proxy force of the Soviet Union, and called for a policy of diplomatic isolation and economic and political pressures as long as Hanoi's troops remain in Cambodia.

New Zealand's view appears to be based in part on reports of increasing friction between Vietnam and the Soviet Union and on hopes, which are harbored by several Asian countries, that the leaders in Hanoi eventually can be weaned away from dependence on the Soviets.

Thailand's foreign policy analysts, among others, have noted signs of Vietnamese restiveness about their Soviet patrons, including recent unhappiness that Thai officials sent a message to Hanoi through a Soviet intermediary.

A senior Thai official added that the reports of Vietnamese dissatisfaction with Moscow are not surprising, since "the longer they [the Soviets] stay in a country, the more friction they usually have."

The Far East Economic Review has recently reported notable gaps and strains between Vietnam and the Soviets, especially in Cambodia where the Soviets appear to be creating a direct line of authority to the Phnom Penh government, cutting out its Vietnamese sponsors. Reflecting a similar view, Singapore's deputy prime minister, Sinnathamby Rajaratnam, wrote in the Asian Wall Street Journal earlier this month that Vietnam "has lost the war for a Vietnamese Kampuchea [Cambodia] to the Soviets."

Neither the Southeast Asians nor the New Zealanders have expressed disagreement with the policy of strongly opposing the Vietnamese occupation of Cambodia with a variety of pressures. But, at the same time, there have been private expressions of concern that too harsh a line might reduce Vietnam's ability eventually to distance itself from Moscow.

Much of the discussion here between Haig and his Australian and New Zealand counterparts in the 30-year-old regional pact concerned ways to counter the increased Soviet military presence in East Asia. Haig explained the U.S. intention to increase its naval and other military strength in order to play a stronger security role, and according to U.S. sources, the other two ANZUS members agreed to maintain existing forces in Southeast Asia at least for two more years.

Australia has said it will phase out two Mirage jet squadrons currently based in Malaysia, and New Zealand has not announced how long it will maintain its infantry battalion based in Singapore. According to the New Zealand foreign minister, Haig stressed the political importance of maintaining these units. U.S. sources said it became clear in the meetings that the units will be maintained.

Haig also asked Australian officials, reportedly with some success, to deploy the country's aircraft carrier on frequent missions to the Indian Ocean as a contribution to Western naval strength in that area.

The secretary of state also discussed possible contributions by both Australia and New Zealand to a multinational force of troops to police the Sinai Desert after the scheduled withdrawal of Israeli military forces next spring under the Egyptian-Israeli peace treaty.

The United States plans to contribute about half of the 2,500-man force, but is seeking to recruit other nations to contribute to the opened police duty. Although Australia and New Zealand have been cool to the plan because of concern for Arab reaction, their foreign ministers indicated today that discussions with Haig have moved them closer to acceptance of what Haig described as very modest participation by them in specialized roles in the Sinai force.