French President Francois Mitterrand, paying a brief but politically charged visit to this troubled island territory, conferred today with leading supporters and opponents of independence from France in an effort to defuse the volatile situation here.

Leaders of both sides later issued statements sharply critical of the Mitterrand government and indicated that his visit had changed nothing.

After spending 12 hours in the South Pacific territory, less than half the time it took him to fly here, Mitterrand left for France insisting that all parties to the dispute agreed that "dialogue" should continue.

But in a move indicating that the crisis is emerging as a key issue in the political maneuvering before French parliamentary elections next year, senior opposition politicians, including former president Valery Giscard d'Estaing and former prime minister Jacques Chirac, will visit the island, New Caledonia's neo-Gaullist deputy, Jacques Lafleur, announced today.

Mitterrand's meetings with the rival leaders, who initially said the talks had been useful, came after he was greeted by a massive outpouring of sentiment against independence. About 30,000 people -- approximately half Noumea's population -- demonstrated in the capital in favor of keeping New Caledonia part of the French republic. Mitterrand later flew by helicopter to two towns on New Caledonia's east coast and visited a local tribe.

While the demonstration was aimed mainly at showing attachment to France, and many in the crowd waved French flags, some demonstrators were openly hostile to Mitterrand and his Socialist government. When a military helicopter brought the French president into Noumea from the airport amid tight security, some in the crowd yelled slogans such as "Mitterrand get out."

Among the critical banners were some reading, "Mitterrand traitor," and one that said, "Mitterrand don't sell the South Pacific to the Russians."

Most of the demonstrators were European settlers, who account for about 37 percent of the territory's 145,000 population. But large numbers of Polynesian and Southeast Asian immigrants also attended. In the minority at the rally were members of the native Kanak, or Melanesian, community, most of which supports independence. The Kanaks, who make up about 43 percent of New Caledonia's population, live predominantly in the countryside.

Right-wing opposition parties have accused the government of abandoning its responsibilities in New Caledonia, one of the few remaining outposts of a colonial empire that once stretched from the Caribbean to the South Pacific. The ruling Socialists have supported a plan to grant the territory independence "in association" with France from January next year in an apparent attempt to resolve the problem before new elections for the National Assembly.

An opinion poll to be published Sunday in a Paris newspaper, Journal du Dimanche, suggested that the Socialist president may have succeeded in gaining the upper hand in the debate at least in the short term, Washington Post correspondent Michael Dobbs reported from Paris.

[According to the poll, 44 percent of French citizens have confidence that Mitterrand will find a compromise between the rival demands of the island's residents. Only 31 percent of those questioned said that they did not trust the president on the issue.]

New Caledonia's conservative territorial government and its supporters charged that Mitterrand's Socialist administration is seeking to "abandon" the territory against the will of the majority to the leftist Kanak Socialist National Liberation Front led by Jean-Marie Tjibaou.

In a statement issued tonight, the local government was particularly critical of Tjibaou's departure today on a trip to Australia and France, allegedly with the Mitterrand government's support.

Shortly after his meeting with Mitterrand, the statement said, Tjibaou was taken by a French military helicopter to New Caledonia's Tontouta airport for a flight to Australia, where he is scheduled to meet Foreign Minister Bill Hayden. After a three-day visit to Sydney and Canberra, Tjibaou is scheduled to fly to France to present the case for Kanak independence to various politicians, including conservative opposition figures, Tjibaou's aides said.

The territorial government statement denounced "this new maneuver of the Kanak Socialist National Liberation Front chief who, realizing the great majority of the population rejects him, goes to a foreign country to plead his cause and seek support." It called on French politicians to refuse to meet Tjibaou.

The vice president and spokesman of the territorial government, Yves Magnier, said the trip was being undertaken with the "complicity" of the Mitterrand government and amounted to "a sort of diplomatic offense against our government." He also accused Paris of "facilitating the actions of a rebel government," considering that Tjibaou has formed a "provisional" administration of an independent "Kanaky," the separatists' name for New Caledonia.

In a statement released after his departure, Tjibaou denounced the French government for failing to disarm "the reactionary colonialist population" of the territory. His statement, issued in the name of "Kanaky government," also charged that Paris was "playing a double game," calling for Kanak participation in discussions while it was carrying out "a policy of repression exclusively against the Kanak people."

Since the Kanak front began a campaign of violent agitation in November, about 20 persons have been killed, including 14 Kanak militants.

After Tjibaou's departure, his deputy in the Kanak front, Yeiwene Yeiwene, said Mitterrand had acknowledged in today's discussions "the right of the Kanak people to independence" but noted that he was bound by the French constitution in seeking a solution. No confirmation of this was immediately available, however.

Yeiwene said the Kanak front leaders told Mitterrand that without independence, there would be no security or peace in New Caledonia.

"We explained the problem" to Mitterrand, Yeiwene said. "For us, nothing has changed."

A local territorial government official said the French president "mainly listened" in his meetings with the opponents of independence and "gave no sign of agreement with our thesis."

Mitterrand did not answer questions about the trip in a brief departure statement at the airport tonight. He said that dialogue would continue and praised the work of special envoy Edgard Pisani. Mitterrand said a timetable for an independence referendum in July would be maintained, but he left vague his commitment to particulars of the plan, which has been rejected by both sides.