ANTANANARIVO (Reuters) - Dissident officers declared a takeover of power in Madagascar on Wednesday, but the island’s military leadership vowed to crush any rebellion and security forces dispersed a crowd that had gathered to back the rebels.

Witnesses said about 1,000 people erected a roadblock and set tyres ablaze near military camps housing the rebel soldiers, who said they had formed a ruling committee to run the country, the same day people voted on a new draft constitution.

The security forces stepped in and fired tear gas, chasing the protesters away.

President Andry Rajoelina, who took power in March 2009 with the support of some of the same dissident soldiers, said they threatened to kill him if he did not resign -- but he had refused.

“It’s the people, who are thirsty for change, who made me head of state. And the majority of them accepts me,” Rajoelina told reporters. “No one will pay attention to the declarations of a minority.”

Flanked by the country’s military top brass, Prime Minister Camille Vital told reporters the security forces would ensure the rule of law was upheld.

“They tried to have a coup d’etat but so far everything is under control,” Vital later told France 24 television. “I don’t know what mosquito bit them, but they have broken ranks and committed an error.”

Rebel Colonel Charles Andrianasoavina said earlier at the barracks near the airport that a “military council for the welfare of the people” had been formed to run the world’s fourth largest island.

Colonel Andrianasoavina was one of the main backers of Rajoelina’s power-grab in March last year when he toppled Marc Ravalomanana. Another senior officer behind Rajoelina then was also in the rebel group.

“It’s a war of communiques for now but things could degenerate quickly,” said Madagascar expert Lydie Bokar of the Lille-based political risk consultancy StrategieCo.

DISSIDENT SOLDIERS VOW ACTION

The tension in Madagascar helped push volatile nickel prices 5 percent higher. The island is home to the Ambatovy project which is due to be completed by January 2011 and produce 60,000 tonnes of nickel a year once it hits full speed.

Andrianasoavina told Reuters the dissidents were in control of two adjacent military camps near the airport and that they would defend their positions overnight.

“Tomorrow, representatives from the other camps should join us. We will also go out. But I cannot say what we are going to do,” he said by telephone from the barracks.

“The politicians must launch negotiations to end this saga once and for all,” he said.

Earlier, the rebel colonel told France 24 that the group still planned to seize the presidential palace and shut down the international airport on Thursday.

The country’s military has suffered from rifts since the 2009 coup. A group of dissident military police briefly seized control of a military camp in May, before being quashed by the security forces.

Rebel Colonel Charles Andrianasoavina speaks to the media in Madagascar's capital Antananarivo in this still image taken from video November 17, 2010. REUTERS/Reuters TV

A Reuters witness said it was calm outside the presidential palace in the city’s center and people were strolling about.

OPPOSITION BOYCOTT

Rajoelina scrapped the old constitution after ousting unpopular leader Ravalomanana with military backing, creating turmoil on the island targeted by foreign investors for its oil, nickel, cobalt and uranium deposits.

International mediators brokered a series of power sharing agreements between Rajoelina, Ravalomanana and two other former presidents, but they all collapsed in bickering over the allocation of ministerial posts.

Voters cast their ballots peacefully at more than 18,000 polling stations. Counting has started and the electoral commission is expected to release some partial results later on Wednesday.

Some opposition supporters said they had taken to the streets near the barracks to vent their anger with Rajoelina.

“Whether the result is Yes or No, Rajoelina will be destroyed,” said Nirina Rafenomanana. “We will no longer tolerate what is happening to this country.”

The three main opposition parties, each headed by one of the former presidents, boycotted the referendum.

The new constitution lowers the minimum age for a president by five years to 35, which would regularise 36-year-old Rajoelina’s rule and allow him to renege on a previous pledge that he will not contest the next vote slated for May 4, 2011.

“I just voted because I would like to see changes when it comes to governance. If I had not voted, then there would be no changes. Whether you vote yes or no, you are already on your way to find a solution,” said Aha Randriamahefa in the capital.