The troop movement comes as the Philippine Red Cross asked the Abu Sayyaf for proof that the aid workers were alive.

The three Red Cross workers - Mary Jean Lacaba, a Filipino national, Andreas Notter, from Switzerland and Eugenio Vagni, from Italy - were seized on January 15.

Proof of life demand

Richard Gordon, the head of the Philippine Red Cross, said on Wednesday that he wanted proof from the Abu Sayyaf that the hostages were unharmed.

 The Red Cross has asked for proof the three aid workers are still alive [EPA]
"I want to talk to the three. It is a measure to rebuild confidence,'' he said in a radio interview.

Security officials said a last-ditch attempt by two politicians on Jolo to negotiate the release of the hostages failed on Tuesday after Sakur Tan, the governor of Jolo, declared a state of emergency in the province.

The state of emergency included a curfew, roadblocks and the redeployment of the government forces near the Abu Sayyaf camp.

Tan had said that tanks and truckloads of marines rolled out of a military camp in Jolo towards Indanan to try to surround the group in a jungle area.

But he refused to say if a military rescue was imminent.

Two security officials told the Associated Press on condition of anonymity that the latest developments prompted the kidnappers to delay the threatened killing of one of the hostages.

Until a recent withdrawal, the Abu Sayyaf was surrounded by more than 1,000 government troops.

The Philippine government had conceded to earlier demands by the group and moved its forces back from the camp by 10 to 15km, hoping that the group would release one hostage.

But the group had insisted that the troops must pull back even further - a demand the government said would have led to anarchy.

The Abu Sayyaf has been blamed for some of the country's worst attacks, including the 2004 bombing of a ferry near Manila Bay that killed at least 100 people.

US and Philippine authorities say the group, believed to be behind various kidnappings, has links to Osama bin Laden's al-Qaeda group.