Seven soldiers have been shot dead and seven wounded -- the military's worst casualty toll since the operation was launched on May 19 and martial law was declared in the province on Sumatra island.

"This is the heaviest battle between troops of the Indonesian armed forces and GAM since martial law was imposed in Aceh," said military operations spokesman Lieutenant Colonel Yani Basuki.

The clash began late Monday at Matang Kumbang in Bireuen district and lasted until early Tuesday, Basuki said, with 40 marines and 22 infantrymen battling an estimated 60 rebels.

Aceh military operation commander Brigadier General Bambang Darmono said his troops had killed five rebels, including a woman.

Troops also confiscated one automatic rifle and one rocket propelled grenade, Darmono told reporters while visiting the clash site.

However GAM's chief spokesman, Sofyan Daud, said in Jakarta in mid-afternoon that the fighting had stopped but might flare up again. He told AFP that 32 rebels were involved in the operation and had suffered no casualties.

Spokesman Basuki was later quoted by Koran Tempo newspaper's online edition as saying that two companies, or about 200 men, have been sent as reinforcements.

An officer at military headquarters in Lhokseumawe city said the clash ended on Tuesday morning but the area remained closed to the public because troops were still hunting the rebels.

Twenty soldiers and three policemen have now died in Aceh since May 19. Troops have also killed 160 rebels, according to the military, and more than 300 are under arrest.

Police said 11 of those detained, including five GAM negotiators who were arrested on the eve of crucial peace talks last month, would face charges of subversion and terrorism punishable by death.

The evidence files on the 11 were handed over to prosecutors on Monday to process their indictments, said Aceh police spokesman Sayed Husainy.

"They will all face charges of plotting to overthrow the government and of terrorism," Husainy told AFP in Jakarta.

The five were arrested on their way to last-ditch peace talks in Tokyo between the Indonesian government and GAM, in a move that sparked a strong US protest.

They were freed the following day just as the Tokyo discussions began but were rearrested hours after the talks broke down -- and just before the military launched its major assault against the guerrillas.

In recent months police have accused GAM of being behind several bombings in Jakarta and the Sumatran city of Medan, charges denied by the rebels.

Three soldiers accused of beating up villagers during a search for guerrillas appeared before a court-martial Tuesday in Lhokseumawe.

A military prosecutor recommended jail sentences of between seven months and eight months and 20 days, the state Antara news agency said.

Three other soldiers have already been jailed for four months over the same incident and a second lieutenant will also face a court-martial.

Police accused GAM of abducting 23 village chiefs in the rebel stronghold of Bireuen to force them to resign their posts.

Some 76 other village heads in Bireuen district resigned Sunday, saying they were unable to perform their duties because of harassment from both sides.

GAM, which denied the abductions, has been fighting since 1976 for independence. An estimated 10,000 people, mostly civilians, have been killed since then.

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