There is a ban on services to honour Tamil rebels and remember civilians killed in the conflict, which ended in 2009 after claiming at least 100,000 lives.

In Jaffna, police barricaded the building, preventing politicians from entering, and smashed a banana-tree branch brought to the service in a Hindu religious practice to commemorate the dead, witnesses said.

"They lit camphor lamps just outside the council wall because they could not go in," a witness said, asking not to be named. "But a policeman stamped on the camphor and snuffed out the flames."

There were no reports of arrests in Jaffna, 400 kilometres north of Colombo, but authorities have warned that they would use tough anti-terror laws against those defying the ban.

Government forces declared an end to the 37-year war after killing Velupillai Prabhakaran, leader of the Tamil Tigers, in a final battle in the northeast on May 18, 2009.

Local residents in Mullaittivu district where he died said last week that they would hold private memorials but no public events out of fear of arrest.

Human-rights groups have said at least 40,000 civilians were killed in the final months of the fighting alone and have accused government forces of war crimes, which Colombo strongly denies.

The Defence Ministry said arrangements were in place for today's parade in Matara, the southern heartland of the majority Sinhalese and the birthplace of President Mahinda Rajapaksa.

"All arrangements have been finalised for the holding of the Fifth Victory Day in Matara on Sunday," the ministry said, adding that more than 7,500 troops and police would be deployed.