(CNN Philippines) – Abdul Basit Usman, the country’s most wanted terrorist who was reportedly killed in a clash with the Moro Islamic Liberation Front (MILF) members in Maguindanao on Sunday (May 3), was instead allegedly slain by his own bodyguards in pursuit of a US$1 million bounty on him, the Armed Forces of the Philippines (AFP) said Monday (May 4).

In a press briefing at Camp Aguinaldo in Quezon City, AFP Chief Gen. Gregorio Pio Catapang said: "There was in-fighting among his (Usman) group… Reports reaching this headquarters revealed that Usman and five of his unidentified cohorts were killed in a shoot-out allegedly with fellow members of his group."

Catapang said he had information that Usman's followers had turned on him because of a $1 million bounty offered by the U.S. State Department, without elaborating.

Screenshot of Abdul Basit Usman's profile posted at the Rewards For Justice website (www.rewardsforjustice.net)

Catapang’s account, however, was contradicted by the MILF, which said its fighters killed the renegade Usman.

Usman’s death on Sunday could boost the ongoing peace efforts between the government and the MILF – a pact that could end about 45 years of conflict that has killed 120,000 people and displaced 2 million in war-torn Mindanao.

Related: Who is Basit Usman?

Catapang said Usman was travelling with seven bodyguards towards a rebel camp in Guindulungan town in Maguindano when a firefight erupted within his group.

"The bodies were discovered by Moro Islamic Liberation Front rebels," he said, adding army and police units were trying to establish the identities of the slain militants.

The MILF's chief peace negotiator, Mohagher Iqbal, told Reuters that Usman was killed by its forces when he resisted arrest.

He said Usman's group was intercepted by rebel forces near a creek at around 10:30 a.m. Sunday, but chose to shoot it out rather than be taken to the guerrilla's main camp, he said.

Despite the different versions on Usman’s death, both Catapang and Iqbal, however, said his death would be a boost to the peace efforts.

"Our security operations will continue until we get all the potential spoilers to the peace process," Catapang said, adding there were still 10 foreign Islamist militants and about 100 local renegade Islamist militants in Mindanao.

Reuters contributed to this report.