Three soldiers were killed and 19 wounded in a two-day battle with Islamic militants to free aid workers abducted in the southern Philippines, the military said on Tuesday.
Abu Sayyaf rebels holding the Red Cross workers since January 15 tried to break through a tight military cordon around dense jungle on Jolo Island Monday, resulting in two days of fierce fighting, the military added.
Troops said an undetermined number of militants were killed or wounded, including Albader Parad, the commander holding hostages Mary Jean Lacaba of the Philippines, Eugenio Vagni of Italy and Swiss national Andreas Notter.
"Three soldiers were killed and 19 were wounded in action since yesterday's engagement," said military spokesman Brigadier General Gaudencio Pangilinan.
"The pressure is working. That is why they are trying to get out," he told reporters in Manila. The fate of the three hostages is not known but the military said it had recovered their personal effects from a camp it over-ran Monday.
"We recovered their tents and other equipment," Pangilinan told reporters in Manila.
Pangilinan said the military did not know if the hostages were with the militants when the fighting broke out.
"We know they are intact in one group ... the Abu Sayyaf and the hostages," he said.
"They have moved I think two or three kilometres from the original encounter site."
The three were kidnapped by the Abu Sayyaf, a militant group behind the country's worst terrorist attacks, while on a humanitarian mission on Jolo. Pangilinan said Parad was likely killed after he was hit by a military sniper.
The ICRC said in a statement it was concerned with the ongoing clashes which may have endangered the hostages. Alain Aeschlimann, the ICRC's head of operations in Asia, said he last spoke with the hostages by telephone on March 11.
"The ICRC is aware that an exchange of gunfire took place in the region on Monday, 16 March," Aeschlimann said. "We're very concerned to hear about this development."
While the Abu Sayyaf group has not made public demands for ransom, local officials trying to secure the release of the hostages have quoted a figure of one million dollars. The group is blamed for the 2004 bombing of a passenger ferry that killed over 100 in Manila Bay.
It has kidnapped dozens of foreigners, businessmen and religious workers over the past decade and is on the US government's list of foreign terrorist organisations. The military said an Abu Sayyaf grenade attack on a karaoke bar late Monday on Jolo killed two people and wounded at least four, and indicated it may have been a diversionary tactic.