BBC Correspondent Jeremy Vine in Lesotho: Fighting and looting

Five South African soldiers have been killed, the first to die in active service since apartheid ended.

Another 11 Lesotho soldiers have been wounded in the clashes.

Reports say there are several civilian casualties and hospitals are treating dozens of people with bullet injuries.

Jeremy Vine: Troops encountering resistance

The South African troops had little trouble in dispersing opposition protesters in Maseru, after troops backed by helicopters and heavy weaponry moved in early on Tuesday.

But heavily-armed sections of the Lesotho Defence Force, which sided with opposition, have been putting up stiff resistance. Most of the resistance is centred on the main army barracks.

While the troops were preoccupied with the remaining pockets of resistance in Maseru, looters virtually destroyed the centre of the city.

Buildings were set on fire and the contents of most shops stolen.

At the border post with South Africa, a steady stream of foreigners have been fleeing Lesotho.

Most diplomatic staff have been evacuated and South African citizens have been warned that they could become the target of revenge attacks.

Weeks of violence

The violence followed seven weeks of protests over a disputed election last May. Opposition demonstrators had brought the capital to a standstill.

"The military intervention is at the request of the king of Lesotho and under the auspices of the Southern African Development Community," said South African defence spokeswoman Laverne Machine.

South African defence spokeswoman Lt-Col Laverne Machine: aims and objectives

Lt Col Machine said that contrary to earlier reports, 200 troops from Botswana had not yet arrived but were expected later in the day.

Opposition spokeswoman Mamello Morrison told South African radio from the palace grounds that the intervention would be unpopular with the majority of people in the country.

"President (Nelson) Mandela has sent his soldiers to butcher our people," she said as gunfire erupted in the background.

'Regional support' for intervention

South African Deputy Foreign Minister Aziz Pahad said the intervention was ordered in line with the 14-nation Southern African Development Community's (SADC) policy of supporting governments in power.

"There was a coup in Lesotho and in terms of SADC policy, SADC decided to assist the government to normalise the situation so that political processes can take their course," Mr Pahad told South African radio. He did not say who had staged the coup.

Recent troubles

Lesotho has experienced seven weeks of anti-government protests, some of them violent, after the disputed election.

The oppositon complained that May's general election, which gave the ruling Congress for Democracy 79 out of 80 seats, was rigged.

Earlier in September, 15 senior officers fled Lesotho for South Africa.

They had been arrested by junior ranks and forced to resign in a disagreement over military intervention to end six weeks of unrest in the capital.

A mountainous land-locked country in the middle of South Africa, Lesotho has a population of 2 million people.