Dili – Anti-independence militias have launched a "terrorist strategy" to undermine Timor Leste's government before the planned United Nations withdrawal from the country next year, a top UN peacekeeper said.

Brigadier-General Justin Kelly, deputy commander of the UN peacekeeping force in the world's newest nation, said the killing of five former pro-independence campaigners in a mountain region last month pointed to a new militia threat from Indonesian West Timor.

He said a group of men recently arrested in the town of Liquica claimed that they and another group which carried out those killings were sent into Timor Leste in December from West Timor, along with five other groups.

They named their sponsor as Master Sergeant Tome Diogo, a Timor Leste national working for the Indonesian military in the border town of Atambua. The men said they were among some 300 trained for a guerilla campaign against former pro-independence activists and Suco chiefs, the influential local chieftains.

Brig-Gen Kelly called this a "classical terrorist strategy of trying to separate the people from the government", comparing it to the past campaigns of the Vietcong in Vietnam or the communists in Malaya in the 1950s.

"We more or less expected this would happen but it has happened earlier than we thought," he said. However, he said he thought it was more likely Diogo was working for other Timor Leste nationals in this matter rather than the Indonesian army. Timor Leste leaders have also said they do not believe Jakarta had any hand in the incursions.

Pro-Jakarta militias organised by elements of the Indonesian army organised a brutal intimidation campaign before Timor Leste's August 1999 vote to break away from Jakarta and a revenge campaign afterwards.

The militias fled across the border to West Timor before peacekeeping troops arrived. An estimated 3,000 former militiamen are still there.

Many of the militia leaders come from influential Timor Leste families and some are wealthy. But they face legal action for crimes committed in 1999 if they return home.

The infiltration, coming on top of riots late last year linked to internal dissent, could herald a dangerously enlarged role for Timor Leste's military, some analysts say.