JAKARTA - Acehnese rebels celebrated the 27th anniversary of their independence struggle yesterday with the sporadic raising of flags and a rare battlefield success, killing four soldiers and injuring two in clashes across the restive province.

The Indonesian military, which launched a fresh offensive against the Free Aceh Movement (GAM) in May, had warned that anyone celebrating the anniversary would be punished severely. They threatened to shoot anyone caught raising a rebel flag and said offenders would be charged with treason.

Troops staged helicopter and road patrols to stop GAM members from raising rebel flags.

The threats and increased military patrols in the oil- and gas-rich province appeared to work, with witnesses seeing only a smattering of rebel flags - black and red with a star - flying across the province on the northern tip of Sumatra.

Soldiers took down several flags raised in the Nagan Raya area in west Aceh, the state Antara news agency said.

Two soldiers were killed and two were injured in fierce fighting that started on Wednesday in a mountainous region of eastern Aceh, said Lieutenant-Colonel Joko Warsito.

Two other soldiers were killed in gunbattles in western Aceh, he said.

No rebels were hurt yesterday, he added, although seven were killed a day earlier in separate fighting.

Yesterday's killings marked one of the few days that the Indonesian army lost more men than rebels and came after months of military dominance on the battlefield.

The GAM had in previous years invited journalists to cover its anniversary flag-raisings and parades and called general strikes which shut down much of the province.

This year, the province is under martial law, with 40,000 police officers and troops mounting an all-out drive to crush the guerillas.

Shops and offices remained open and buses were operating yesterday.

'In the past, people were afraid to go about their activities as usual because they were threatened with violence. Under martial law, the people have nothing to worry about,' an Aceh military spokesman, Colonel Ditya Sudarsono, told AFP.

'Aceh has been under military control and there's nothing that the rebels can do now.'

Since the May offensive began, the military claims it has killed more than 1,000 rebels but lost only 47 soldiers and 16 police officers.

A rebel spokesman could not be reached for comment.

Rebels launched their independence campaign in 1976 after the Indonesian government reneged on promises to give the province increased autonomy.

Fighting intensified in May after peace talks collapsed amid accusations that the rebels were taking advantage of a lull in violence to regroup.

About 12,000 people have died in the conflict. (AP, AFP)