MANILA, Philippines >> A day after proclaiming the death of a top regional terrorist suspect in a U.S.-backed airstrike, the Philippine military acknowledged Friday that his remains still have not been found.

Troops were searching the jungle camp that was hit Thursday for the body of Malaysian Zulkifli bin Hir, also known as Marwan, said regional military spokesman Lt. Col. Randolph Cabangbang.

Military officials said at least 15 people were killed in the dawn strike on a militant camp on remote southern Jolo Island, including two other high-level leaders. A national military spokesman, Col. Marcelo Burgos, initially reported that Marwan was among them.

Marwan’s death would mark a major success in disrupting the Jemaah Islamiyah terror network blamed for some of the most spectacular bombing attacks in Southeast Asia in recent years. But if the initial report proves incorrect, it would turn a largely successful strike into a partial embarrassment for the Philippine military, while burnishing the reputation of the elusive terrorist.

The U.S. has offered a $5 million reward for the capture of Marwan, a U.S.-trained engineer accused of involvement in deadly bombings in the Philippines and in training militants.

Cabangbang said the announcement of Marwan’s killing was based on information provided by informants. He refused to elaborate, saying it would compromise intelligence assets.

"We are still searching. Our troops are still there," Cabangbang said.

He suggested that the blast could have obliterated Marwan’s body, saying the process of verification linked to the possible disbursement of the reward money to informants will be "more tedious" and could include DNA testing.

Two Philippine security officials with knowledge of the airstrike who spoke to The Associated Press also said Marwan’s body was not found, though bombs shattered the house where he was believed to have been.

One of the officials confirmed the deaths of the other two high-level leaders: Umbra Jumdail, who led the Philippine-based Abu Sayyaf militant group, and a Singaporean leader in Jemaah Islamiyah, Abdullah Ali, who used the guerrilla name Muawiyah. The other official confirmed only the death of Jumdail, also known as Dr. Abu Pula, and his son.

Both officials spoke on condition of anonymity because they were not authorized to talk to reporters.

Cabangbang said the decision to announce the killings, including that of Marwan, was made by the chief of staff of the Armed Forces of the Philippines, Gen. Jessie Dellosa, after he was briefed by commanders.

"There are details that we cannot divulge because of operational security," he said when pressed for details.

A U.S. official in Washington confirmed the strike on Jolo Island, an impoverished region 600 miles (950 kilometers) south of Manila, and said the Pentagon provided assistance in one of the region’s most successful anti-terror operations in years. The strike debilitated a regional militant network that has relied on the restive southern Philippines — sometimes called Southeast Asia’s Afghanistan — as a headquarters for planning bombings and a base for training and recruitment.

About 30 militants were at the camp near Parang town on Jolo, the stronghold of the Abu Sayyaf and their allies from the mostly Indonesian-based Jemaah Islamiyah, when it was bombarded by two OV10 aircraft with 500-pound (227-kilogram) bombs at 3 a.m., regional military commander Maj. Gen. Noel Coballes said.

"Our report is there were at least 15 killed, including their three leadership," he said. "This is a deliberate, fully planned attack coming from our forces."

The rest of the militants escaped and no one was captured, Coballes said.

American counterterrorism troops have helped ill-equipped Filipino troops track Marwan for years using satellite and drone surveillance. About 600 U.S. special forces troops have been deployed in the southern Philippines since 2002, providing crucial support for the Philippines’ counterterrorism operations. U.S.-backed Philippine offensives have been credited for the capture and killing of hundreds of Abu Sayyaf fighters and most top leaders since the 1990s.

In Washington, a U.S. official, speaking to the AP on condition of anonymity because he was not authorized to speak on the record about the operation, confirmed the Pentagon had aided the strike. He was not specific about the contribution and did not know how many people had been killed in the operation.

Marwan’s death would represent the most important success against Jemaah Islamiyah since the January 2011 arrest of Indonesian suspect Umar Patek in Pakistan’s garrison town of Abbottabad, where Osama bin Laden was killed in a U.S. commando attack four months later.

Patek and Marwan allegedly collaborated with the Abu Sayyaf in training militants in bomb-making skills, seeking funding locally and abroad and plotting attacks, including against American troops in the southern Philippines.

Patek is believed to have returned to Indonesia then gone to Pakistan, leaving Marwan to take charge in the southern Philippines, military officials say.

The attack in Jolo also represents a huge blow to the Abu Sayyaf’s ability to recover from years of setbacks through fund raising and training of militants.

Abu Sayyaf is behind numerous ransom kidnappings, bomb attacks and beheadings that have terrorized the Philippines for more than two decades.

Jumdail had eluded troops in numerous offensives and emerged as a key figure in the radical movement.

Most recently, all three of the militant leaders were among the prime suspects in the kidnappings of three Red Cross workers from Switzerland, Italy and the Philippines in 2009. The hostages regained their freedom months later.

Abu Sayyaf militants, numbering about 400 by military estimates, are still considered a key threat to regional security and are suspected in the kidnapping of a former Australian soldier, as well as a Malaysian, a Japanese and an Indian.

On Wednesday, gunmen in nearby Tawi-Tawi island province seized Dutch and Swiss tourists. Officials said they were trying to move the hostages to Jolo.

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Gomez contributed from Bangkok. Associated Press writers Oliver Teves in Manila, Philippines, and Pauline Jelinek in Washington contributed to this report.