The Philippine military on Monday said it was keeping up pressure on the Islamic militants holding captive a Red Cross worker from Italy and hopes he will be released "sooner than anticipated".
Eugenio Vagni was nabbed on southern Jolo island in mid-January along with fellow International Committee of the Red Cross (ICRC) workers Andreas Notter of Switzerland and Mary Jean Lacaba of the Philippines.
Notter was rescued unharmed by troops on Saturday, while Lacaba was safely freed on April 2.
But more than three months on, 62-year-old Vagni is still being held by Abu Sayyaf gunmen and there are growing fears for his physical and mental health.
"There's no let-up in our campaign to apply the appropriate pressure on the kidnappers of Vagni," said Lieutenant Colonel Edgard Arevalo, a spokesman for the military operations against the kidnappers.
"With all odds being with the security forces, we expect Vagni could be released by his captors sooner than anticipated," Arevalo said in a statement, without providing further details.
Interior Secretary Ronaldo Puno said Muslim clerics sent to the Abu Sayyaf are meanwhile trying to convince the gunmen to allow the government to send doctors to check on Vagni.
The Italian is said to be needing an operation for a hernia and officials have said the harsh jungle environment he has been confined to has also taken its toll on his emotional state.
Puno said negotiators spoke with Vagni on the phone on Sunday, adding that about 50 Abu Sayyaf militants are known to guard the hostage.
The Abu Sayyaf is a small group of militants on the US government's list of foreign terrorist organizations.
It is blamed for the Philippines' worst terrorist attacks, as well as for a string of high-profile abductions targeting foreigners in the past decade.