Canada's Foreign Affairs Minister Lawrence Cannon is calling on the government of Sri Lanka and the Tamil Tigers to declare a ceasefire after fighting between the two sides killed at least 52 civilians in the past day, according to UN estimates.

Government forces have been battling the Liberation Tigers of Tamil Eelam (known as the Tamil Tigers) for 25 years. The group has been fighting for a separate homeland for Sri Lanka's minority Tamil population.

About 70,000 people have died during the campaign, which has escalated in recent months.

"Canada calls for the Government of Sri Lanka and the Liberation Tigers of Tamil Eelam (LTTE) to declare and honour an immediate ceasefire to allow full, safe and unhindered access; the evacuation of the sick and wounded; and the delivery of much-needed humanitarian assistance to civilians," Cannon said in a statement.

The U.S. and British governments have also called for a temporary ceasefire to allow civilians to leave the conflict area.

Over the last several weeks, government troops have closed in on Tiger strongholds and have pushed rebels to an 85-square-kilometre patch of land on the northeast coast, where about 250,000 Tamil civilians are now trapped.

Local health officials say more than 300 civilians have died in the recent fighting, a figure the government denies.

On Tuesday, fighting in and around a government-designated safe zone killed 52 civilians and wounded 80 more, according to UN officials.

Civilians have also come under fire from shell attacks at the Puthukkudiyiruppu hospital, where hundreds of wounded civilians had sought refuge.

After the area was hammered for nearly 16 hours by artillery fire on Wednesday, the Red Cross evacuated the hospital, which was the only medical facility in the region.

Cannon said that Canada "strongly condemns" the attacks on the hospital and the safe zone.

The UN also claimed Wednesday that troops have used cluster munitions during attacks in the war zone. This is the first time the Sri Lankan military has been accused of using the weapon, which can cause damage to a large area.

As well, many of the bomblets do not immediately explode, which means civilians can sustain injuries long after the fighting ends.

Military spokesperson Brig. Udaya Nanayakkara denied the charges, saying "we don't have the facility to fire cluster munitions. We don't have these weapons."

Cannon calls for political solution

Only a negotiated settlement, and not a military campaign, will settle the conflict, Cannon said.

He endorsed a statement released Tuesday by the co-chairs of the Tokyo Donor Conference on Reconstruction and Development of Sri Lanka that proposes conditions to prevent more civilian casualties and establish a final political settlement.

"Canada supports the co-chairs' call for the LTTE to discuss with the Government of Sri Lanka the terms for ending hostilities, including the renunciation of violence, the laying down of arms, and the acceptance of the Government of Sri Lanka's offer of amnesty, as the first step toward an inclusive political dialogue that can contribute to a lasting peace," he said.

On Wednesday, demonstrations were scheduled across Canada and around the world to protest conditions for civilians caught in the crossfire and put pressure on governments to intervene.

In Germany, more than 4,000 people marched toward Berlin to protest the fighting. They chanted slogans such as "Stop the Genocide" and asked the German government to pressure Sri Lanka to end the fighting.

The latest developments came as Sri Lanka marked its 61st Independence Day with a military parade in the capital, Colombo.

With files from The Associated Press