Dili – The UN mission in East Timor said Friday it has seen Indonesian military-backed militia burning houses and intimidating people, posing a "serious obstacle" to a vote on the territory's future.

"Our team encountered three separate groups of Besih Merah Putih (Red and White Iron) militia accompanied by and indeed directed by TNI (Indonesian army) soldiers carrying out operations in the area," Ian Martin, head of the UN Mission in East Timor (UNAMET) said. The training was witnessed in the Liquisa district west of Dili Thursday, he said.

A third militia group was seen "burning personal property, assaulting an old man and seeking to drive villagers out of Leotela village against their will," he said.

"That is exactly the kind of incident of which we have received extensive reports." Martin said the incidents helped explain the "extensive internal displacement" of people especially in the western districts of East Timor.

"Most of these people are not in concentrations, but are being driven from one village to another. But it is clear that there are tens of thousands of internally displaced people at the moment giving rise to very serious humanitarian concerns and also of course a serious obstacle to the registration exercise which is the first major practical part of the consultation," Martin said.

Whether the intimidation would force a delay in the scheduled August 8 vote when East Timorese decide between independence or autonomy was being discussed at the UN headquarters, he added,

"I can't say anything at the moment about a delay. Obviously that's under discussion in New York," said Martin, speaking before flying to Darwin, Australia where he is to meet the first group of UN police to arrive in Dili on Saturday.