Zamboanga City, Philippines  - Muslim militants freed a Sri Lankan peace advocate after more than four months in captivity in the southern Philippines, police said Thursday.

Umar Jaleel, a civilian peacekeeper working with the Brussels-based Nonviolent Peaceforce, was released late Wednesday by Abu Sayyaf rebels in Tipo-Tipo town in Basilan province, 900 kilometres south of Manila.

Provincial police chief Senior Superintendent Salik Macapantar said Jaleel was released through negotiations and pressure from security forces who cordoned off the kidnappers' hideout.

He said the 38-year-old Sri Lankan was turned over to police by local residents.

"He looks sickly, very thin and he kept saying in Arabic 'Praise be to Allah,'" Macapantar said.

Jaleel was abducted on February 13 from the office of the Nonviolent Peaceforce in Lamitan City.

His release was "accomplished nonviolently and without payment of ransom," said Mel Duncan, executive director of Nonviolent Peaceforce.

"We are grateful and relieved for the safe return of Mr Umar Jaleel," Duncan said. "We are not discouraged by this traumatic event. This is even more reason to intensify our efforts in supporting local work that promotes peace and coexistence."

Abu Sayyaf rebels are still holding captive three public school teachers and a lending firm employee in Basilan. In the nearby island of Jolo, the guerrillas have been holding an Italian Red Cross worker since January.

Aside from being responsible for a number of high-profile kidnappings in the Philippines, the Abu Sayyaf rebels has been blamed for some of the worst terrorist attacks in the country. (dpa)