MANILA - A leader of Islamic militants and his two brothers were killed in an ongoing fight against government forces in Butig, Lanao Del Sur.

Relatives of Omar Maute, one of two leaders of the militant Maute Group, confirmed Sunday that a bomb killed him last February 21.
The explosion also left his younger brother Matti Maute dead.

Another brother of the rebel leader was killed in a separate encounter.

Other members of the Maute family, however, are still putting up a fight, the military said.

The other leader of the group, Abdullah Maute, is allegedly still alive along with three brothers.

The Maute group was formerly known as the Khilafah Islamiyah Mindanao, with ties to the Southeast Asian terror group Jemaah Islamiyah.

The Armed Forces has yet to verify information on the possibility that the Butig militants have links with the Islamic State terror group.

More than 20,000 people have been displaced while three soldier were killed during a week of clashes.

The military said the group's base, a concrete building on the outskirts of a remote town in a mountainous region of violence-racked Mindanao island, had been overrun on Thursday night following helicopter gunship attacks.

However, a local reporter on the scene said clashes continued throughout Friday.

Up to 61 militants were believed to have been killed, although only three bodies had been recovered, according to the military chief with responsibility for the area, Colonel Roseller Murillo.

Murillo and other military officials said they had no firm evidence to confirm the other 58 reported deaths, and would not say how they came up with the number other than that they relied on intelligence reports.

Malacañang on Saturday assured assistance for displaced residents in the conflict-torn town. -- Report from Chiara Zambrano, ABS-CBN News; Agence France-Presse

(READ: Palace assures help for civilians displaced by Lanao clashes)