Jakarta – Indonesia will not agree to an international probe into the massacre of 31 people in strife-ridden Aceh province because it would infringe upon its sovereignty, Foreign Minister Hassan Wirayuda said on Monday.

"We rule out the possibility of sending an international team to Aceh," Mr Wirayuda said. "The international community is aware this is a purely domestic problem."

The Indonesian military and guerillas of the Free Aceh Movement have accused each other of carrying out Thursday's killings in a palm-oil plantation in eastern Aceh. On Saturday, a separatist leader, Amri Abdul Wahab, demanded an unbiased international probe, saying it would be the only way to determine which side was guilty.

The massacre by unidentified gunmen came as government forces escalated their offensive against separatist rebels who have extended their control over wide swathes of the countryside during the past two years.

Thursday's killings – the bloodiest single incident since Indonesian troops executed 54 teenage students at an Islamic school in 1999 – coincided with President Megawati Sukarnoputri's announcement of her first Cabinet.

Many analysts have predicted that Ms Megawati, a staunch nationalist, will reverse former President Abdurrahman Wahid's efforts to reach a negotiated settlement with the rebels, and instead give the army a free hand in their campaign to crush the insurgency.

The generals have opposed Mr Wahid's policy of talking to the rebels. Last month, security forces defied his orders and arrested six rebel negotiators who had been granted safe passage by the government.

More than 6,000 people have been killed in the past decade in the gas and oil-rich province on the northern tip of Sumatra. At least 1,000, mostly civilians, have died so far this year.

On Sunday, senior security minister Susilo Bambang Yudhoyono said a preliminary investigation by police had determined that the rebels had shot the farm workers. He accused the insurgents of "seeking to attract international attention".