Jakarta – Timor Leste faces the worst threat to its stability since independence as security forces counter raids by armed gangs from Indonesia's West Timor.

Militiamen, who murdered six villagers early this month, have infiltrated the nation – known formerly as East Timor – with the aim of destabilising it, a government official said yesterday.

"They did not accept the results of the 1999 referendum. The Indonesians did but they did not," said Mr Jose Guterres, Chief of Staff to East Timorese Prime Minister Mari Alkatiri.

He said the militiamen now operating "have nothing to do with the Indonesian government" which ruled East Timor for 24 years up to 1999.

On January 4, 12 to 15 men armed with M-16, SKS and G-3 rifles killed six people in the villages of Tiarelelo and Lobano, about 35km from the Indonesian border, said Brig-Gen Justin Kelly, deputy commander of the United Nations peacekeeping force stationed here. 'We have detected a number of armed bands, some of them who seem to incorporate former militia members, who are conducting criminal operations in East Timor,' he said.

"It's a serious situation." There had been little militia activity in East Timor for about two years.

President Xanana Gusmao, speaking to reporters in Dili yesterday, did not rule out militia involvement but tied the murders to frustrations among his people.