Toronto's Tamil community came out en masse to draw attention to the Sri Lankan government's military offensive aimed at crushing the separatist Tamil Tigers, spilling onto Front Street outside Union Station for a time.

By 6:30 p.m., Front Street had cleared, allowing traffic to flow again.

Friday's event was the second major protest on Toronto's streets in the last 24 hours, with a large protest held downtown on Thursday night.

The protesters were attempting to construct a human chain from Yonge and Bloor Streets to Union station on Front Street before travelling back up University Avenue to Bloor Street. That distance is about five kilometres.

They held up signs with messages such as "Stop the Tamil genocide in Sri Lanka." They could be heard chanting "We want justice!" as media vehicles drove by.

Const. Wendy Drummond of the Toronto Police told that the demonstrators had been very peaceful and orderly, although they worried about the prospect of congestion when the demonstration breaks up. She said police don't provide crowd estimates.

A civil war has ebbed and flowed in Sri Lanka since 1983. The rebels, formally known as the Liberation Tigers of Tamil Eelam, are fighting for a separate Tamil homeland in the country's north.

Tamils are a minority in Sri Lanka, which sits just over 30 kilometres offshore from the south tip of India. The Sinhalese form the majority. They are Buddhists. Tamils tend to be either Hindu or Roman Catholic. Tamils speak Tamil while the Sinhalese speak Sinhala.

According to Statistics Canada's 2006 census, just under 94,000 people in the GTA claim Tamil as their mother tongue. About 5,800 claim Sinhala.

In 2002, the combatants signed a ceasefire agreement brokered by Norway, with peace talks failing in 2006 -- the same year the Canadian government declared the Tamil Tigers to be a terrorist organization (the U.S. made the declaration in 1997).

In January 2008, the Sri Lankan government withdrew from the ceasefire agreement, with fighting  subsequently escalating in the last 12 months. In September, it ordered the withdrawal of UN and most humanitarian organizations from the conflict zone in the country's northeast.

Earlier this month, government forces captured Kilinochchi, long a Tamil Tigers stronghold. Sri Lanka's President Mahinda Rajapakse called on the rebels to surrender.

But the battling is taking a toll on non-combatants.

On Wednesday, Human Rights Watch called on both sides to allow an estimated 250,000 civilians trapped in the conflict zone safe passage out and to allow them to obtain desperately needed humanitarian aid.

HRW, one of the world's major human rights watchdogs, has accused the Tigers of not allowing civilians to flee. When they do flee, the Sri Lankan military has arrested those civilians and slapped them in militarized detention camps.

"Civilians are scrambling for shelter in an area that is under heavy artillery fire, including many children, wounded, and elderly who need urgent assistance," said Brad Adams, HRW's Asia director. "The UN and concerned governments should press Sri Lanka to take all necessary steps to spare civilians from harm."

The full picture isn't emerging because the Sri Lankan government has slapped restrictions on the movement of journalists and human rights monitors.

The Sri Lankan military has claimed it has killed no civilians and is only targeting rebel forces.