Police stormed Tamil-majority areas of the capital under the cover of darkness and forced guests at low-budget hostels to get into buses escorted by armed men, residents said.

Police had last week announced they would provide transport for minority Tamils to return to their homes in the island's embattled northern and eastern regions unless they could prove they were employed in Colombo.

The crackdown is part of efforts to stop the Liberation Tigers of Tamil Eelam (LTTE) infiltrating the city of 600,000 people, police said. There was no immediate comment from the government.

"This operation is a very bad example," Tamil political leader Dharmalingam Sithadthan said.

"It is OK for the LTTE to indulge in this sort of ethnic cleaning because they have no moral responsibility, but a government can't behave like this," he said.

He said the police move reminded him of how the Tamil Tigers had evicted thousands of minority Muslims from the northern peninsula of Jaffna in 1990.

"Tamil people have been rounded up by the police and I believe they are being taken back to their villagers in the northeast," Sithadthan said.

Police sources said nearly 50 buses had been deployed for the pre-dawn operation.

Last week, police Inspector-General Victor Perera said Tamils from the embattled northern and eastern provinces were spending long periods of time in Colombo without any work and that they were a threat to national security.

"Those who are loitering in Colombo will be sent home. We will give them transport," Perera said. "We are doing this to protect the people and because of a threat to national security."

Thousands of Tamils from revolt-hit areas arrive in the capital monthly in the hope of obtaining passports to travel abroad for employment or secure political asylum overseas.

But Tamils are required to obtain permits from the police to travel to the rest of the country under a de facto visa system put in place to prevent Tiger rebels infiltrating the capital.

The guerrillas, who have been fighting for a Tamil homeland for 35 years, were blamed for two bomb attacks that killed nine people and wounded 44 in and around the capital last month.

Official sources said the government was further tightening up restrictions with the deployment of cameras to photograph anyone leaving the embattled north and east and travelling to the rest of the country.

The evictions reverberated in the national parliament, where ethnic Tamil lawmakers held up proceedings to protest, officials said.

"Tamil MPs were protesting against the police forcibly taking away the Tamils in buses," a parliamentary official said. "The MPs sat in the well of the House and the sittings were held up as a result."