MANILA, July 8 (Xinhua) -- At least 45 militants have been killed and 28 others injured since the military launched fresh offensive on June 1 against the Bangsamoro Islamic Freedom Fighters (BIFF) in southern Philippines, the military said on Sunday.

Brig. Gen. Cirilito Sobejana of the Army's 6th Infantry Division, based in Maguindanao province, said the army has so far launched 10 major "sustained military operations" against the BIFF, an extremist group with links to Islamic State (IS) fighters.

He said four soldiers have also been killed and 20 others wounded in the clashes.

"We've been conducting the operation for a month and eight days already," Sobejana said.

During the continuing military operation, he said the military recovered 28 assorted firearms and 10 improvised explosive devices. The troops also managed to capture four rebel camps and an IED and firearm making facility, he added.

Sobejana vowed to continue the military offensive against the BIFF, expressing hope to destroy the terrorist group.

There are up to 400 BIFF terrorists operating in Mindanao, he said.

BIFF members are mostly disgruntled former members of the larger insurgent group Moro Islamic Liberation Front (MILF) which signed peace accord with the government.

The BIFF is among the several groups in Mindanao that pledged allegiance to the Islamic State a few years ago.