By Hader Glang

ZAMBOANGA CITY, the Philippines

At least one solider has been killed and four others injured in ongoing fighting with a Daesh-linked militant group in the Philippines’ troubled south, according to the military Thursday.

Maj. Filemon Tan Jr., Western Mindanao Command spokesman, said in a statement that the Abu Sayyaf fighters also suffered undetermined casualties in the latest firefight.

Operating troops were reportedly conducting combat operations in Sumisip town in the island province of Basilan at around 5.10 p.m. (0910GMT) when they encountered an undetermined number of heavily armed men led by Abu Sayyaf leader Furuji Indama.

According to Tan, clashes were ongoing at the time of the report and other military units, including the air force, had been alerted to reinforce and launch "indirect fire".

"Troops have been advised to move closer towards the encounter site in order to reinforce and block possible enemy withdrawal routes. As of now, airstrikes and firefight continue," he said.

Earlier this week, President Rodrigo Duterte instructed troops to crush the Abu Sayyaf and other Daesh-linked groups in six months to put an end to kidnappings and bombings in majority Muslim provinces in southern Mindanao.

Since 1991, the Abu Sayyaf -- armed with mostly improvised explosive devices, mortars and automatic rifles -- has carried out bombings, kidnappings, assassinations and extortion in a self-determined fight for an independent province in the Philippines.

The group is notorious for beheading victims after ransoms have failed to be paid for their release,

It is among the militant groups in the south that have pledged allegiance to Daesh, prompting fears during the stalling of a peace process between the government and the Moro Islamic Liberation Front rebel group that it could make inroads in a region torn by decades of armed conflict.