Manila - The International Committee of the Red Cross (ICRC) said Thursday it has lost contact with its three staff who were abducted a week ago by Muslim militants in the southern Philippines.

The ICRC said the last time their three abducted workers - Swiss Andreas Notter, Italian Eugenio Vagni and Filipino Mary Jean Lacaba - were able to call was on January
19.

The three victims had just visited the provincial jail on Jolo island, 1,000 kilometres south of Manila, when gunmen blocked their vehicle and seized them on January 15.

"We hope that we'll hear their voices again soon and that they remain unharmed," said Alain Aeschlimann, ICRC head of operations for East Asia, South-East Asia and the Pacific in Geneva. "We also continue to hope that this difficult situation will have a positive outcome."

"I appeal to those who are holding Mary Jean, Andreas and Eugenio to let them go as quickly as possible," he added. "We want to have them back safe and sound. Their children, spouses, parents, siblings and loved ones are anxious and waiting for them to come home."

Military and police sources said the Abu Sayyaf rebels have moved their hostages to the jungles of Talipao town from the nearby town of Indanan.

Police said initial investigations showed that the three Red Cross staff members were seized by gunmen led by a sacked jail guard who then turned them over to Abu Sayyaf.

According to military intelligence sources, the kidnappers were led by commanders Albader Parad and Akmad Jumdail, who were planning to demand 5 million dollars in ransom for the safe release of the hostages.

US Ambassador to the Philippines Kristie Kenney also appealed to the kidnappers to release unharmed the three ICRC staff.

"We call immediately on those who have taken them to release them now," she said. "We stand ready to assist within the limitation of our roles here."

Hundreds of US troops have been stationed in several areas in Mindanao, including on Jolo, to train Filipino troops in the counter-terrorism.

The al-Qaeda-linked Abu Sayyaf rebel group has been blamed for some of the worst terrorist attacks in the Philippines.

It is also notorious for high-profile kidnapping-for-ransom cases, including the abduction of 21 European tourists and Asian workers from a Malaysian resort island in 2000. The hostages were ransomed for millions of dollars before they were freed months later. (dpa)