MANILA, July 11 — At least 14 Philippine marines were killed late Tuesday in some of the heaviest fighting with Muslim insurgents in the southern part of the country in recent months, officials said Wednesday.

Military officials said that they had recovered the bodies of 14 marines after clashes with suspected Abu Sayyaf militants in Tipo-Tipo, a hinterland town on Basilan island, and that at least 10 of them had been beheaded.

A marine spokesman, Lt. Col. Ariel Caculitan, said in Manila that 50 marines had clashed with more than 300 rebels. “We were totally outnumbered,” he said.

Maj. Gen. Ben Mohammad Dolorfino suggested that the beheadings might have been in retaliation for the slaying of the son of one of the rebel group’s leaders.

However, leaders of another group, the Moro Islamic Liberation Front, said that it was its own fighters who had fought with the marines and that they had killed 23 of them. But the front’s spokesman, Abu Majid, said the front’s fighters had not beheaded the marines. He said this was done by “unidentified groups” after the fighting. He said four rebels had been killed and seven wounded.

Mr. Majid also said the violence could have been avoided had the government troops, who had entered the area in search of a kidnapped Roman Catholic priest from Italy, consulted with his group. “We have all the mechanism in the cease-fire that allows coordination and to prevent this kind of unfortunate incident,” he said.

The military said the marines had been trying to check out reports that the priest, the Rev. Giancarlo Bossi, who was kidnapped last month in Zamboanga Sibugay Province, also in the southern Philippines, had been taken to Basilan.

The Moro Islamic Liberation Front has been fighting for a separate Islamic state for Filipino Muslims in the south for three decades; a cease-fire is in effect, although there have been violations. The agreement requires both sides to coordinate their movements if one side ventures into an area where the other side is present. Mr. Majid said he did not understand why the marines had not notified the front of its operations in Tipo-Tipo.

Mohaqher Iqbal, the leader of the group’s negotiating panel, said: “Our troops thought they were under attack. That’s why they fought back. It should not have happened.”

The Philippine government had said that some elements of the Moro Islamic Liberation Front were also working with Abu Sayyaf and Jemaah Islamiyah, groups that have been blamed for some of the most horrific terrorist attacks in the country since 2001.

The front has denied any connection with Abu Sayyaf or Jemaah Islamiyah, but promised to purge its ranks of extremists.

Copyright 2007 The New York Times Company