OTTAWA - More than 10,000 Tamil protesters packed the front lawn of Parliament today, calling on the Harper government to pressure Sri Lanka to stop a military assault in their homeland.

The lawn was a sea of umbrellas as protesters beat drums, chanted, and listened to speakers amid a steady drizzle.

Demonstrators began arriving in the capital early this morning in buses and cars.

Police guided traffic around the swell of peace activists and Tamil community leaders carrying signs and waving Canadian flags.

The demonstrators want Canada to do more to force the Sri Lankan government to end its offensive against the last stronghold of the Tamil Tigers, which is reported to have killed thousands of civilians.

A much smaller group of Tamils has been protesting on Parliament Hill for about two weeks.

They have sometimes snarled Wellington Street, the principal east-west thoroughfare that runs in front of Parliament and have also waved the red flags of the Liberation Tigers of Tamil Eelam (LTTE), which is listed as a terrorist group by the Canadian government.

There were no signs of the flags at Tuesday's protest, with leaders hoping that might convince politicians to address the crowd.

The protesters claim a genocide is occurring in Sri Lanka as the decades-long struggle between the Sri Lankan government and the Tamil Tigers draws to a close.

The Sri Lankan military says about 35,000 civilians have fled the last corner of Tiger-held territory and the government has warned the rebels a final assault is imminent.

Sri Lanka's Tamil rebels said Tuesday that 1,000 civilians died and nearly 2,300 were wounded in a government raid on their territory. The military denied the accusation, saying the action freed thousands of noncombatants from the war zone.

Government forces say they rescued thousands of civilians Monday after they broke through a barrier built by the rebels to protect their territory. By Tuesday evening, the military said 52,000 had escaped.

But as troops have pushed the rebels into an ever-shrinking sliver of territory, both sides have accused the other of endangering civilians.

Rights groups say the rebels are holding many against their will to use as human shields. But those groups have also accused the government of indiscriminate shelling in the tightly packed region in its bid to end the 25-year war. Both sides deny the other's allegations.

The United Nations estimates 100,000 civilians are trapped in the a war zone measuring just 20 square kilometres and it says about 4,500 non-combatants have been killed in the last three months.

The Ottawa demonstrators are demanding Canada impose economic sanctions on the Sri Lankan government and expel the country's high commissioner.

The Tamil Tigers have been linked to assassinations and are considered the first modern-day organization to popularize the practice of suicide bombings. The group's followers are widely credited with designing the suicide vest, now used most commonly in the Middle East.