DILI, Indonesia, Oct 11, Reuter - Security to prevent a possible guerrilla attack against Pope John Paul is so tight in East Timor that local priests fear many believers will be too frightened to attend his mass on Thursday.

"They are intimidated by all the security, all the checkpoints. Come without the right paperwork and you are in trouble," said a priest who accompanied 2,000 parishioners to the capital, Dili, from the far east of the island, an area considered guerrilla territory.

Earlier estimates expected up to 400,000 people to attend the Pope's mass, but local priests said they thought it unlikely more than 150,000 Timorese would show up.

"Ordinary people in Timor are as scared as ever of being picked up by the military," the priest said.

The pontiff's visit to the former Portuguese colony is the most controversial part of his five-day tour of Indonesia, which has been fighting a diminishing band of pro-independence guerrillas there for 13 years.

Indonesian Defence Minister Benny Murdani on Tuesday night said there were fewer than 500 guerrillas still battling Jakarta but they were a dangerously unpredictable force.

"We are taking extra security measures for very obvious reasons. If one of those jokers comes down from the hills with a hand-grenade...," Murdani said.

Indonesia sent troops into East Timor after the Portuguese abandoned 400 years of colonial rule in 1975 as local conflicts slid towards civil war.

Some 14,000 troops are stationed in East Timor, fighting the Fretilin (Revolutionary Movement for an Independent East Timor) who are demanding the right to self-determination, once promised by Lisbon to the territory's 600,000 inhabitants.

Jakarta's rule is not recognised by the United Nations, or by the Vatican, amid accusations Indonesia illegally detains, tortures and executes Timorese thought to oppose integration.

Diplomats said Jakarta hopes the visit will legitimise its claim to the overwhelmingly Catholic province, although the Pope has stressed that his presence there is purely pastoral.

Murdani declined to say whether the Pope's visit signalled implicit recognition of Jakarta's sovereignty, telling reporters: "I dare not even answer that question."

He said he was not apprehensive about the tour, although the leader of the Roman Catholic Church is frequently blunt in calling on governments to respect human rights.

"We know who the Pope is, what he stands for and has been working for all his life," said Murdani, a Catholic and one of five Christian cabinet ministers in Indonesia, which defends fiercely a policy of religious freedom in a country where 85 per cent of the population is Moslem.

"Let him see for himself," Murdani said.

The Pope is likely to see a warmly enthusiastic people.

Foreign journalists arriving three days before the pointiff were greeted at the airport by schoolchildren gaily waving waving red-and-white national flags.

Flags flutter from poles and trees along the route from the airport to the site of the mass, said by locals to be the scene of bloody battles in the fight for independence.

The 1,800 km (1,100 mile) journey over more than half the sprawling Indonesian archipelago took five hours.

The Pope, who was met by the regional governor, was due to say mass, scheduled to last two-and-a-half hours at a stadium five km (three miles) from the airport.

Nearly 90 per cent of the 1.3 million people on the island, which was colonised by the Portuguese and later the Dutch, are Catholic.

The road from the airport was lined with people shouting "Welcome the Holy Father" and carrying little crosses or pictures of Mary and Jesus.

A hundred dancers in costume on the road gave the Pope a traditional welcome.