COLOMBO, Sri Lanka — Hundreds of ethnic Tamils have been rounded up and forced from Sri Lanka's capital by the government. Officials said the move was a needed security measure as its fight with Tamil rebels intensifies but offered no evidence the people expelled posed a threat.Human rights groups warned the move against Tamil civilians could be the start of an "ethnic cleansing" campaign.

The more than 300 Tamils expelled from Colombo in the past three days were sent back to their homes in the Tamil-dominated north and east, areas that have been wracked by bloodshed for most of the past year as Sri Lanka's vicious ethnic war flared anew.

The fighting continued yesterday when soldiers clashed with Tamil Tiger rebels near the eastern city of Batticaloa and at least five rebels were killed, the military said. The battle took place near a district where a Japanese peace envoy was visiting Tamils displaced by conflict.

The rebels, who routinely dispute government accounts of clashes, offered no immediate comment.

Clashes have intensified in the past 19 months between government forces and the rebels in the north and east. The Tigers are fighting for a separate homeland for the country's 3.1 million minority Tamils, who have suffered decades of discrimination by successive Sinhalese majority governments.

Colombo, in the south, has been subjected to rebel suicide bombings and air raids in recent months but spared the intense, day-to-day fighting seen in the north and east.

Still, the city slowly has been transformed into a fortified capital with soldiers lining the main thoroughfares. Officials said the expulsions were just the latest security measure.

"We conducted a routine search operation and found these people were staying in Colombo without a valid reason," said a senior police officer, Rohan Abeywardena.

The Defence Ministry insisted the operation did not specifically target Tamils. But the only people rounded up were Tamils.

The ministry said they were all taken from cheap guest houses, adding: "Investigations have also confirmed that those responsible for these brutal killings have hatched their brutal plans and executed them from these 'lodgings,"' — a reference to recent bombings in the capital.

It did not say if any of the people rounded up were suspected in the bombings, only noting that many had been "lodging" in Colombo for over six months without employment and could not provide a valid reason for being in the capital.

Since the war began in 1983, hundreds of thousands of Tamils have fled Sri Lanka and most of those rounded up were believed to be waiting for passport and visas so they could work in or move to other countries.

Human rights activists decried the government's move.

"These Tamils have been denied their right to live in Colombo," Sirithunga Jayasuriya, chairman of Civil Monitoring Committee, a human rights group.

"This is like ethnic cleansing and we strongly condemn it," he added.

Opposition lawmakers also criticised the move saying it violated Tamils' fundamental rights. Parliament sittings were suspended for an hour amid protests by Tamil and other minority lawmakers.

More than a quarter of Colombo's 800,000 people are Tamil.

The expulsions were believed to be the first ever carried out by the government.

But in 1983 the government provided ships to transport thousands of Tamils to the north and east after anti-Tamil riots that helped spark the war.

The Tigers forcibly evicted tens of thousands of Muslims, the country's second largest minority group, from the Tamil-majority Jaffna peninsula in 1990, alleging they were co-operating with security forces.