Philippine troops have killed at least seven militants from the Abu Sayyaf group in a raid on their hideout in the south of the country, officials say.
An army commander said they believed the men might be linked to a wanted Malaysian militant - Zulkipli Bin Hir, also known as Marwan.
Bodies are being identified. It is not clear whether he was among the dead.
He is said to be one of the leaders of a key militant group in the region, Jemaah Islamiah (JI).
A Philippines soldier was also wounded during the raid on the island of Siasi, near the main island of Jolo, Brig Gen Rustico Guerrero said.
"We caught them by surprise," Gen Guerrero told reporters.
He said 15 assault rifles and bomb-making materials had been seized.
"We have information that Zulkifli bin Hir, alias Marwan, was hiding with the Abu Sayyaf group on the island, but we are not sure whether he was there during the raid," Gen Guerrero said.
The US has offered a $5m (£3.2m) reward for information leading to the capture of Marwan, who is said to have been behind a series of bomb attacks in the southern Philippines since 2006.
He is believed to have trained Muslim rebels in making bombs.
Abu Sayyaf is the smallest and most radical of the Islamic separatist groups in the southern Philippines.
JI has links to al-Qaeda and has a long track record of bomb attacks in Indonesia.