An Australian Hercules C-130 transport plane touched down in Dili at about 0040 GMT (0140 BST) on Monday carrying 30 Royal Marines, 20 Australian troops and large amounts of equipment.

The Marines are believed to be members of the elite Special Boat Squadron (SBS), the maritime equivalent of the SAS, although the Ministry of Defence refused to confirm this.

The troops will be joined later by around 250 Gurkhas.

The BBC's Ben Brown reports: "The situation is uncannily similar to Kosovo"

About 25 Indonesian army troops met the peacekeepers at Dili airport. But there was no sign of the militias and all seemed calm in the city.

The UK troops, who drove off the planes in Land Rovers mounted with light machine guns, immediately fanned out to secure the airport and vital road links.

Armed Forces Minister John Spellar said the second objective would be to take the militias off the streets.

The Ministry of Defence refuses to say if the Marines are SBS men

The next stage would be to get "vital facilities", particularly water, working again, he told BBC Radio 4's Today programme.

Mr Spellar said the UN soldiers did not appear to have met with any resistance from the militias so far.

Indonesia has reportedly pulled out 80% of its 7,000 troops from the area, but Mr Spellar said it was "very difficult to assess" how many had actually left the territory.

"The militias may be a difficulty but at the same time they are now faced, not with women and children and unarmed civilians, but with well-organised, well-trained, well-disciplined forces," he said.

A lot of work was being done to get supplies in and the operation was going "very well at the moment", he added.

Trained in Britain

Asked about the controversial sale of Hawk fighter jets to Indonesia by Britain, Mr Spellar said the UK government could do nothing to prevent the three planes being delivered to Indonesia.

Indonesian pilots train to fly a British Hawk jet

However, he said that the planes would have "no impact at all" on the situation in East Timor "because the Indonesian military are co-operating."

He also confirmed newspaper reports at the weekend that 24 senior Indonesian military personnel had been trained in Britain since the May 1997 election.

However, he said that the training had "nothing to do with direct military operations", but would instead have taught the running of a "proper, well-disciplined military under civilian control".

Thousands are homeless

The International Force for East Timor (Intefet) has been given the task of taking over control of East Timor from Indonesian troops, who failed to prevent a murderous rampage by pro-Jakarta militias following the referendum on autonomy.

Thousands of Timorese were killed by the militias - who were composed of settlers from other parts of Indonesia - and more than 300,000 people driven from their homes.

The Australian-led ground troops will be supported by nine heavily armed warships including the British guided missile destroyer, HMS Glasgow.