Manila  - The International Committee of the Red Cross (ICRC) urged Muslim militants in the southern Philippines to spare the lives of three Red Cross workers amid a threat to behead one of the hostages on Tuesday.

The Abu Sayyaf rebel group has given the Philippine government until Tuesday afternoon to meet a demand to pullout all soldiers, policemen and militiamen from practically the entire Jolo island, 1,000 kilometres south of Manila.

But the government said it was impossible to meet the demand, and the rebels said they will behead one of three Red Cross hostages - Swiss Andreas Notter, Italian Eugenio Vagni and Filipino Mary Jean Lacaba - by Tuesday afternoon.

The ICRC appealed to the Abu Sayyaf not to harm the three workers, who were abducted on January 15 after visiting the provincial jail on Jolo to oversee a water and sanitation project.

"Our message to the Abu Sayyaf is please spare and release Mary Jean, Eugenio and Andreas," ICRC President Jakob Kellenberger said in a statement. "All they were doing was helping people in need in your area."

Pope Benedict XVI also appealed to the Abu Sayyaf to release the hostages and for authorities to work for a peaceful solution to the crisis.

On the weekend, soldiers, policemen and militiamen already pulled out from Indanan town in a bid to save the hostages, giving the rebels around 130 square kilometres to move around freely.

When the military cordon was up, the kidnappers were restricted to only about 30 square kilometres in the jungles of Indanan.

Under the new demand, government forces would be limited to the capital town of Jolo.

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