Ethnic Tamil politicians have complained that more than 2,000 Tamils were rounded up by security forces in Colombo and its suburbs after last Wednesday's bombings, which killed 20 people and were blamed on the Tamil Tiger rebels.
After meeting Monday with the relatives of some of those detained, President Mahinda Rajapaksa ordered police to release all those being held who were not charged with a crime, according to the president's office.
Military spokesman Brig. Udaya Nanayakkara, who declined to release arrest figures, said authorities were complying with the president's directive.
"People have been released," he said. "People had been questioned and once their identities had been established they have been released."
Tamils have repeatedly complained that they were being singled out by the Sri Lankan security forces, which are dominated by the Sinhalese majority.
"They are desperate, and they think every Tamil is a terrorist ... that's why they are doing random arrests," said Kanagalingam Sivajilingam, a lawmaker for the Tamil National Alliance party. "We are very angry, people are so angry."
Government officials told the Tamil lawmakers that they had released more than 2,000 of those detained in recent days and were still holding about 400, Sivajilingam said, adding that his party had not verified those figures.
In June, authorities rounded up hundreds of Tamils staying at hostels in Colombo and expelled them from the capital. Amid an international uproar, the government let them return two days later.
The Tamil Tigers have fought since 1983 for an independent homeland for Tamils in Sri Lanka's north and east following decades of discrimination at the hands of successive Sinhalese dominated governments. More than 70,000 people have been killed in the conflict.
Fighting across the north - where the Tamil Tigers control a de facto state - has intensified in recent months, following the government's victory over the rebels in the east in July.
Army troops launched an attack against a rebel position in the Muhamalai region of northern Sri Lanka on Monday evening, killing five rebels and destroying two bunkers, the military said Tuesday.
Another 42 rebels and six soldiers were killed in other battles Monday, the military said.
In the worst attack, rebel fighters attacked soldiers in a bid to recapture land the military seized over the weekend, Nanayakkara said.
The military repelled the attack in a battle that killed 35 rebels and six soldiers, he said.
Troops also killed seven guerrillas in two other separate clashes, in which the military suffered no casualties, Nanayakkara said.
Rebel spokesman Rasiah Ilanthirayan said large battles had taken place in the north, but that the military's death tolls were inaccurate. He did not give his own figures, saying they were not yet available.
Each side routinely exaggerates the other's casualty numbers and plays down its own. Independent confirmation was impossible due to restricted access to the conflict zone.
"We should use shock therapy to sober up the Americans. In this case, the Americans will speak about the need to resume dialogue. There is no other option"
The United States is concerned about the current crisis in the relations with Russia and suggests returning to reasonable policies to avoid a nuclear war