Sri Lankan police have arrested two rights activists under an anti-terrorism law to prevent them from spreading "communal disharmony" in the country's war-torn northern region, ahead of voting on a resolution against the country at the UNHRC.

"Two people were arrested at 10.30 last night under the provisions of the Prevention of Terrorism Act. They were acting so as to promote communal disharmony," police spokesman Ajith Rohana said.

The arrests came ahead a key meeting of the UN Human Rights Council in Geneva later this month that is expected to pass a US-sponsored resolution against Sri Lanka over its alleged rights abuses during the ethnic war with LTTE rebels.

Human rights groups said the arrested activists were Father Praveen, Director of the Jaffna-based Center for Peace and Reconciliation and Ruki Fernando of the Colombo-based INFORM, a human rights documentation center.

They were arrested from the northern town of Kilinochchi. The Kilinochchi's police chief said: "Ruki Fernando and Rev Praveen behaved in a suspicious manner as they visited some families of those who have lost their family members."