New Zealand premier vows antinuclear activity in second term. Elections bring sweeping victory for Labour Party

New Zealand's Labour government is expected to launch a worldwide campaign for nuclear disarmament following its sweeping victory in Saturday's general election. Prime Minister David Lange, whose antinuclear policy has already caused a rift with New Zealand's old ally the United States, made it clear before the election that he intends to take his campaign onto the international stage.

The Reagan administration has long been concerned that the New Zealand policy, which has effectively barred US ships carrying nuclear weapons from visiting this country, would spread to other allies. Mr. Lange has pledged not to interfere in the internal politics of other countries, but he said: ``New Zealand's stand against nuclear weapons has given us a substantial platform from which to advance the cause of nuclear disarmament.''

He told a press conference Sunday that New Zealand had a businesslike relationship with the US but it was not likely to get any friendlier. ``It's about as warm as it's going to get,'' he said.

The election result reaffirmed widespread popular support for the government's antinuclear policy, which featured prominently in the campaign largely dominated by the economic issues.

The opposition National Party recognized this support when it announced that it would also keep New Zealand nuclear-free, trusting the US not to send nuclear weapons, but not asking it to breach its policy of neither confirming nor denying their presence on US ships.

National Party leader Jim Bolger claimed during the campaign that Labour would move to a nonaligned policy if re-elected, but Lange strongly denied this.

In winning another three-year term in office, Labour retained its 15-seat majority in the 97-seat House of Representatives, finishing with 56 seats, compared with National's 41.The poll saw the demise of the main third party, the New Zealand Democrats who lost their two seats in parliament.

It was an historic victory, with Lange becoming the first Labour leader to win two successive elections since 1946.

The size of Labour's win surprised analysts who had predicted a much smaller majority. The government's far-reaching reform of the economy on free-market lines has hurt many - inflation is at a record 18.9 percent, interest rates top 20 percent, and unemployment is rising.

But voters accepted Labour's appeal for more time to finish the job, and its promise that the reforms would work and would raise living standards. Lange promised Sunday that he would concentrate on traditional Labour issues like education, housing, health, and social welfare.