Lindsay Murdoch, Jakarta – Activists in Aceh have called off anti-Jakarta protests planned for Saturday because they fear Indonesia's armed forces will use flag-raising rallies as an excuse for a brutal crackdown.

But top Indonesian army officers in the province are intensifying a push for the introduction of martial law, claiming that separatist rebels are already in control.

Colonel Syafnil Armen said an order by President Abdurrhman Wahid for troops to remain in their barracks "made the military feel mad and stressed". "How can we do our job if there is an order like that?" Reuters quoted him as saying.

More than 11,000 police have been sent to the staunchly Islamic province at the northern tip of Sumatra as the outlawed Free Aceh Movement (GAM) approaches its fourth anniversary.

Mr Mohammad Nazar, the co-ordinator of the Information Centre for Aceh's Referendum, said in the provincial capital, Banda Aceh, that supporters would gather only for prayers on the December 4 anniversary. The umbrella group, which represents 104 organisations, brought together more than 750,000 people on November 8 to rally for an East Timor-style referendum in one of the biggest anti-Jakarta gatherings ever held in Indonesia.

"Basically we are not preparing anything because GAM has sent letters to the people not to raise GAM's flag," Mr Nazar said. "So I think the military will be deceived."

Indonesian police and military chiefs brushed aside accusations of past human rights abuses and warned they would crush any separatist movements.

The military's chief spokesman, Major-General Sudrajat, said: "For those who obviously want to break away from Indonesia or take up arms to revolt, there's no other choice for the TNI [the military] but to crush them.

"We should not be deceived by human rights issues and accusations which are based on perception and certain political agendas."

Earlier the National Police Chief, General Roesmanhadi, said 11,000 policemen had been deployed in Aceh because of the possibility of a mobilisation of masses, the lowering of the Indonesian flag and attacks on military and police posts and state-owned companies.

Colonel Armen, one of two military commanders based in Aceh, said the situation in the province was not safe as rebels "are present in every corner". "This is their way to show the Government what they want, as they demand a referendum to be independent."

In the latest of a series of ambiguous statements about Aceh's future, Mr Wahid said his Government would formulate a new policy on the province by the end of December, but any referendum would not include an option for independence.