After meeting the president here Thursday, the watchdog group's Secretary General Irene Khan said an escalation of rights abuses over the past 18 months had shown domestic institutions were not up to the task.

"A climate of fear dominates Sri Lanka, with human rights activists and journalists threatened, attacked, intimidated, harassed and killed. Even humanitarian workers have not been immune," she said in a statement.

"In this deteriorating situation, an independent presence to monitor and investigate human rights abuses by all sides is critical," Khan said.

She urged Rajapakse to open talks with the UN High Commissioner for Human Rights on monitoring and investigating rights violations.

More than 5,000 people have been killed since December 2005 as fighting has escalated despite a 2002 ceasefire.

Amnesty International said that during the past year more than 1,000 people are believed to have been "disappeared" and the same number had been unlawfully killed.

President Mahinda Rajapakse of Sri Lanka and senior Sri Lankan officials said Friday that they were taking their own steps to find the truth behind recent killings of humanitarian workers and alleged rights violations.

However, Rajapakse stopped short of responding directly to an appeal Amnesty International made to him Thursday, to invite UN monitors to verify claims of human rights violations by both sides in the country's bitter ethnic civil war.