Manila - The Philippine military has tightened a security cordon around Muslim militants holding captive an Italian Red Cross worker, officials said Monday.

Italian Eugenio Vagni, 62, was one of three Red Cross workers kidnapped by Abu Sayyaf rebels on Jolo island, 1,000 kilometres south of Manila, on January 15. He is reportedly suffering from a hernia injury.

The rebels have freed Vagni's two colleagues, Swiss Andreas Notter on April 17 and Filipino Mary Jean Lacaba on April 2.

Marine Lieutenant Colonel Edgard Arevalo said troops were repositioning to "add pressure" on the kidnappers.

"We are re-aligning the deployment of our personnel based on (the kidnappers') movements," he said. "As much as possible, we are trying to contain them in a more or less smaller location so that they can be easily located."

The three Red Cross hostages were abducted after visiting the Jolo provincial jail to oversee a water and sanitation project.

Abu Sayyaf rebels earlier threatened to behead one of the hostages if the military did not pull out from a large part of Jolo island.

The guerrillas have been blamed for some of the worst terrorist attacks and high-profile kidnappings in the Philippines. They also have beheaded hostages, including an American tourist abducted in 2001, when authorities failed to meet their demands. (dpa)