Sri Lanka’s government on Sunday marked the fifth anniversary of its civil war victory over ethnic Tamil separatists by displaying the country’s military strength, while preventing Tamil civilians from publicly remembering their dead.

The government’s approach highlights the deep ethnic polarisation that remains in this island nation despite the end of the quarter-century civil war.

President Mahinda Rajapaksa presided over a Victory Day ceremony in the southern coastal town of Matara where military personnel paraded in the streets with tanks and artillery guns, while fighter jets flew overhead.

In the country’s ethnic Tamil-majority north and east, however, military troops surrounded political party and newspaper offices in an apparent attempt to prevent public memorials for those who died in the war.

Sri Lanka’s military defeated Tamil Tiger rebels in May 2009, ending the long civil war. Heavy civilian casualties and allegations of serious human rights violations, especially in the final months of the fighting, prompted the United Nations Human Rights Council this year to sanction an international inquiry into the conduct of both sides.

According to initial U.N. estimates, between 80,000 and 100,000 people were killed in the conflict. However, a later U.N. report suggested that as many as 40,000 ethnic Tamil civilians may have been killed in the last months of the fighting alone.

Peace groups and the government’s own war commission had warned against holding major victory celebrations, saying they could further alienate Tamil communities. They instead advised the government to have a solemn memorial for all victims of the war.

“Our country is once again leaving space to the people in the north to develop their own structures to deal with their sorrows and issues, which will contribute to a separate state of mind,” the National Peace Council, a local activist group, said in a statement. “There is no peace when there is victory and defeat side by side on the same issue.”

“No wise country celebrates war victory after a civil war,” it said.

In a speech on Sunday, Mr. Rajapaksa defended the celebration. “To celebrate this great victory is a duty of a grateful nation,” he said. “Hence, irrespective of objections from anyone, irrespective of who participates or not, we should celebrate this great victory forever.”