Police have broken up a training session by Indonesia's official human rights commission in Aceh province, where the military is in its sixth month of a major offensive against separatist rebels.

More than 20 police armed with rifles descended on the Hotel Paviliun Seulawah Monday afternoon where training in monitoring rights violations had been under way since Sunday, according to witnesses cited by the Serambi daily in Banda Aceh.

"That program was stopped on the orders of the martial law authority. They launched their activity without notification," Banda Aceh police chief Alfons Toluhula was quoted as saying by the newspaper.

He denied a statement by M.M. Billah, who heads the National Commission on Human Rights (Komnas HAM) Aceh team, that authorities had been advised of the training.

Komnas HAM's chairman, Abdul Hakim Garuda Nusantara, was quoted in the Media Indonesia daily as saying he would file a formal complaint against the police.

"This program was an official Komnas HAM activity and Komnas HAM is an official state institute ... It's precisely the police who have violated the law and there is a legal consequence. Komnas HAM will prosecute them," Media Indonesia quoted Nusantara as saying.

Serambi reported that Billah refused to stop the meeting, leading to an exchange of words and negotiations with the police who wanted to take him to headquarters for questioning.

Aceh police spokesman Sayed Husainy told AFP in Jakarta Tuesday that Billah was not detained. He said the Komnas HAM meeting had been shut down Monday and had not resumed Tuesday.

In an interview with Media Indonesia, martial law administrator Major General Endang Suwarya said Komnas HAM is not forbidden from conducting training or other activities in Aceh. "It's just that we appeal to them to ask permission and notify the martial law authorities," he said.

About 30 people including non-governmental organization representatives, journalists, police officers and civil servants from the provincial department of justice and human rights were attending the seminar, scheduled to last until Thursday.

In a July report Komnas HAM accused the military of extra-judicial killing and said its operation appears to be failing to win the hearts of the Acehnese people.

Martial law authorities have restricted the activities of foreign journalists and non-governmental organizations in the province, where Indonesia on May 19 launched its biggest offensive since the 1975 invasion of East Timor.

The military says more than 900 Free Aceh Movement rebels have been killed since the start of its campaign, along with 66 members of the security forces. More than 1,800 rebels have been arrested or have surrendered, the military says.

Martial law was initially expected to last six months but the military has suggested its operation should be extended.