The opposition Social Democrats regained control of Hamburg's city government today, dealing a blow to Chancellor Helmut Kohl's conservative party.

According to official provisional results, the Social Democrats won an absolute majority of 51.3 percent of the vote, compared with 38.6 percent for Kohl's Christian Democratic Union and 6.8 percent for the third party in the city parliament, the Green environmentalist group.

This northern industrial port traditionally has been a Social Democratic stronghold, but the results disappointed Kohl's party, which has been pressing for March 6 national parliamentary elections in the belief that its popularity is on the rise.

"This is a clear setback . . . it is a surprise for us," the Christian Democrat's mayoral candidate, Walther Leisler Kiep told reporters after hearing the results from West German television stations.

Former chancellor Helmut Schmidt, a Hamburg native and Social Democrat who was ousted by parliament Oct. 1 in favor of Kohl, told reporters that he was satisfied.

"It [the results] would be good for the entire Federal Republic of Germany in the coming March election," he said.

The city elections have no direct effect on Kohl's center-right government in Bonn, but they were the first major test of the government's popularity since it took office in October.

The Hamburg Social Democrats, led by Mayor Klaus von Dohnyani, won 64 of the 120 seats in the Senate of the city, which is one of West Germany's 10 states. The Christian Democrats won 48 seats.

"This is a personal defeat for Kohl and for the antisocial politics that have come from Bonn over the past few weeks," said von Dohnyani. "It's a victory not only for me, but for the whole party, and especially Schmidt, who was very active in this campaign."

A stalemate has existed in Hamburg since the June 6 election when all three parties failed to receive an absolute majority and prevented formation of a goverment coalition.

The Social Democrats' new majority -- up from 42.7 percent in June -- means they will not need to form a coalition with the Greens, a group of ecologists opposing nuclear power who are considered too radical by many regular voters in both the major parties.

The liberal Free Democrats, whose switch of support to the Christian Democrats in Bonn brought Kohl to power, slumped to under 3 percent in Hamburg, well below the 5 percent required to win assembly seats. It was the third state election this year in which they failed to qualify for seats in the legislatures.

The result means an end to the "Hamburg conditions" under which the Social Democrats, running a minority government, made vain attempts to reach a working agreement with the Greens. Talks between the two parties collapsed in October, leading to today's elections.

"Hamburg voters have shown what they think of scare talk about red-green chaos and ungovernability," said a Social Democratic spokesman.

But Franz Josef Strauss, leader of the Christian Democrats' Bavarian sister party, the Christian Social Union, insisted on television that voters had not demonstrated dissatisfaction with Kohl's policies but rather with the way the government came to power.

Politicians from all parties said sympathy for Schmidt, who is still the nation's most popular politican, according to polls, had played a large part in the outcome.