Indonesian troops have also been accused of firing shots near the peacekeepers.

A BBC correspondent described the situation in Dili as "extremely tense".

In one incident some 30 pro-Indonesian militias sped by the United Nations compound in three trucks firing semi-automatic weapons in the air.

BBC's Jonathan Head: "Gurkhas going into every house - guns at the ready"

An Australian patrol was forced to flee and British Gurkha troops were given orders to shoot if necessary, but did not return fire.

Under their mandate, they may only open fire if directly attacked.

The commander of the British contingent of the peacekeeping force, Brigadier David Richards, is reported to have accused Indonesian troops of firing shots near his soldiers.

Brigadier Richards also denied that any of the international troops had fired shots.

The BBC's Clive Myrie: "Today the calm was shattered"

In another incident, a house in which Australian troops are billeted is reported to have come under sniper fire.

There were no immediate reports of casualties in this or several other incidents of shooting.

Gunfire was also reported near the city's sports stadium, and at Dili's port, a vital link for the peacekeepers to unload men and supplies.

Three suspects are reported to have been detained.

Militia activities

The commander of the UN force, Major-General Peter Cosgrove, said he was closely monitoring reports of a build-up of pro-Indonesian militias across the border in West Timor.

There are also reports of about 500 militiamen gathering in the town of Liquisa, west of the capital Dili. The militia said they would mount an attack on foreign peacekeepers, witnesses reported.

The stench from the well was overpowering

General Cosgrove said he was accelerating the deployment of his force, which now has about 3,000 troops - half of the total contingent - in East Timor.

Peacekeepers are closely monitoring reports that militias were amassing in the neighbouring Indonesian province of West Timor.

On Wednesday, evidence of systematic atrocities carried out by the militiamen against the East Timorese emerged.

A BBC correspondent was shown what appeared to be a torture and execution centre where up to 30 victims were killed then beheaded and dismembered before their bodies were thrown into a well.

Click here to see a map of latest developments in East Timor

The discovery came as international peacekeeping troops pushed further into the devastated territory and militia groups stepped up their activities.

Some 150 multinational troops have now established a presence in the second city Baucau - their first major advance outside Dili since the arriving on Monday.

But the situation in most of the country is still said to be very dangerous.

Eurico Gutteres, commander of one of the most notorious anti-independence militia, was quoted by Indonesia's official news agency on Wednesday as saying East Timor might be plunged into a civil war.

Warehouses ransacked

People have flooded back from the mountains to Dili, after peacekeepers moved into the city.

Thousands of refugees remain in West Timor

Thousands of people were displaced and whole towns destroyed when the militias, backed by Indonesian troops, went on the rampage to punish those who voted for independence last month.

Returning refugees ransacked government-run warehouses in Dili, carrying away sacks of rice and sugar, and barrels of cooking oil.

Australian peacekeeping forces managed to regain control of the warehouses, but only after most of the food had gone.

Aid flights were suspended as the military build-up got under way because of a lack of space at Dili airport and a shortage of aircraft.

Despite the return of some refugees, thousands remain in hiding in forests and mountains.

The multinational force has so far secured Dili port, the airport and the UN headquarters. Several warships have also arrived.

An Australian military spokesman said Indonesian soldiers were expected to have withdrawn completely from the territory by Sunday.

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