Philippine President Rodrigo Duterte brought in a special guest on Friday to rally troops battling Islamic State followers in the south -- US action hero Steven Seagal.

The star of 80s and 90s hits like "Hard to Kill" and "Under Siege" joined Duterte in a visit to an army camp on the island of Jolo.

He was there to impart martial wisdom to soldiers fighting the feared Abu Sayyaf, a band of Muslim extremists, some of whose members have pledged allegiance to the Islamic State group.

"I know you guys put your life on the line every day. I myself have done and will do the same thing so I understand this is serious business," he told the soldiers, who have been battling Abu Sayyaf for decades.

The extremist group has been blamed for some of the worst terror attacks in the country's history including mass kidnappings and deadly bombings.

Some of its members took part in the five-month battle that devastated the southern city of Marawi this year.

"I believe there is a formula that can help the armed forces, the police, the intelligence network to combat this very, very well," Seagal said.

"I am looking forward to discussing these things with President Duterte at a later time," he added.

Although his military background outside Hollywood is questionable, Seagal lectured the troops on how they would have to steel themselves for a lengthy war of attrition.

"I hope I can be involved with all of you in this war against all of these evil things," he said.

A beaming Duterte praised Seagal, telling the troops "he is a soldier so he is on the same wavelength with you when he talks".

Seagal, whose recent career has largely consisted of direct-to-video movies, apparently bonded with fellow tough-guy Duterte when they met in Manila in October.

He has previously praised Duterte for making the Philippines safer despite widespread criticism that Duterte is resorting to brutal, strong-arm tactics that have claimed hundreds of lives.

Philippine authorities say almost 4,000 "drug personalities" have been killed since Duterte launched a bloody war on drugs after taking office last year.

Source: AFP