A senior Philippine police official said on Monday that police commandos have killed Malaysian Zulkifli Hir, also known as Marwan, one of the world's most wanted and elusive terrorists, but spokesmen for both the police and military have yet to provide official confirmation.
Director Carmelo Valmoria, head of the National Capital Region Police Office, told reporters that Marwan has been "neutralised" in a clash with Muslim rebels on the southern island of Mindanao on Sunday.
But officials have yet to see his body and they still do not know what happened to another suspected Malaysian bomb maker, Basit Usman, who was reportedly also targeted in the police operation.
Colonel Restituto Padilla, the military spokesman, said there is no confirmation that Zulkifli was killed.
At least 50 policemen from the elite Special Action Force (SAF) were reported killed when their units fought with fighters of the Moro Islamic Liberation Front (MILF) in the remote village of Tukanalipao in Mamasapano town.
The police commandos were pursuing a "high-value target" said to be Marwan, according to officials.
The US Federal Bureau of Investigation lists Marwan as among its most wanted terrorists. It has offered a US$5 million (S$6.24 million) reward for his capture or killing.
Marwan, who was trained as an engineer in the US, has been accused of supplying bombs to radical groups like the Abu Sayyaf and training militants.
He is believed to be among those responsible for the 2002 Bali bombings.
Usman is said to be Marwan's apprentice and believed to be responsible for a recent spate of bombings in Mindanao.
Marwan has been reported killed before, during an airstrike in far-flung Jolo island in Mindanao on Feb 2, 2012, along with Abu Sayyaf leader Umbra Jundail, also known as Dr Abu.
No bodies were ever recovered, however, and counter-terrorism officials in Malaysia had always believed Marwan was still alive.
The Philippine military acknowledged in September 2014 that Marwan was still alive, after it was reported that Abu Sayyaf commander Khair Mundo said he saw Marwan in 2013 at a hinterland encampment of the Bangsamoro Islamic Freedom Fighters (BIFF), a hardline separatist group.