Philippine marines made sure there were no foreign or Filipino hostages being held by a large group of Abu Sayyaf militants before engaging the al-Qaida-linked gunmen in a deadly battle two days ago, a military official said Tuesday.

Marine commandant Maj. Gen. Rustico Guerrero said four marines and at least nine Abu Sayyaf militants and allied gunmen were killed in the six-hour gunbattle Sunday in a jungle near southern Sulu province's mountainous Patikul town. Twenty-two other marines were wounded.

Regional military spokesman Lt. Col. Randolph Cabangbang said the marines were deployed in Patikul's hinterlands to check reported sightings of long-held hostages of the Abu Sayyaf.

The militants, notorious for abductions and beheadings, have been blamed for separate kidnappings of two Europeans, a Japanese, a Jordanian and two Filipinos. Military and police officials believe the six hostages are being held in Abu Sayyaf encampments in Patikul and nearby jungle areas.

A former Australian soldier who was kidnapped last December is also believed to be held by Abu Sayyaf gunmen in another southern province near Jolo Island in predominantly Muslim Sulu, about 950 kilometers (590 miles) south of Manila.

Guerrero said the marines took steps to ensure there were no hostages being held by up to 150 Abu Sayyaf militants and allied gunmen before engaging the militants in the fierce battle. The marines got as close as 15 feet (4.5 meters) to the gunmen at one point, he said.

"If there's a confirmed presence of the kidnap victims, we will never go into a shooting war," Guerrero told a news conference at the marines headquarters in Manila where the flag-draped coffins of the slain marines were given military honors.

The Abu Sayyaf militants under commander Radulan Sahiron were backed up by gunmen loyal to Tahir Sali, a commander of a larger rebel group, the Moro National Liberation Front. The two commanders, who maintain camps in Patikul's jungles, have long been suspected of collaborating in ransom kidnappings to raise funds.

Washington has offered $1 million for information leading to Sahiron's capture or killing.

While Abu Sayyaf abductions still occur, they are far fewer today than the massive kidnappings that terrorized Sulu and outlying provinces in the early 2000s when the brutal group still had many commanders and strong ties with terrorist organizations including the Indonesian-based Jemaah Islamiyah.