The Philippines Congress has overwhelmingly approved President Rodrigo Duterte's request to extend martial law by one more year in Mindanao to punish "Islamist and communist terrorists" in the region.

The lawmakers voted 240-27 in favour of Duterte's decision, which will keep the martial law until the end of 2018. This marks the longest period of martial law in the Philippines since the rule of Ferdinand Marcos in 1970s.

Duterte had argued those emergency powers are necessary to totally stamp out extremist forces, which are now regrouping after they have been weakened by a five-month-long military campaign. He said pro-Islamic groups were planning to launch a new wave of terror attacks against the state's security establishments. Besides the Islamic extremists, who have pledged their allegiance to the Islamic State (Isis), Duterte emphasised the "communist terrorists" have also been active in the restive region.

Originally, a 60-day martial law was implemented in May. It was later extended until December 2017. "We are seeing that the rebellion has not stopped, it just moved to another place," said Martial law administrator Defense Secretary Delfin Lorenzana. "The reports are they are actively recruiting again."

The city of Marawi, caught in the centre of a lengthy military campaign witnessed more than 1,000 people, mostly extremists, losing their lives and over 200,000 residents being displaced. "We ask the public to stand behind the administration and rally behind our defenders to quell the continuing rebellion," Harry Roque, Duterte's spokesman, said.

However, Duterte's move has also come under criticism from his political opponents saying the period of the martial law, which bestows enormous powers, is lengthy.

"Is the martial law extension consistent with the Constitution? Our acts must always be consistent with the law and Constitution. This is what distinguishes us from terrorists, criminals or rebels who we seek to defeat," asked Senator Francis Pangilinan.

He added the Filipino president's martial law powers "must not be exercised whimsically and arbitrarily". Other lawmakers have also said the state would end spending billions of pounds on the security measures instead of other requirements such as poverty alleviation programmes.

Philippine President Rodrigo Duterte (l) holds a AK-47 assault rifle as Russian Minister of Defence Sergei Shoigu looks
Philippines President Rodrigo Duterte argued martial law powers are necessary to root out "Islamist and communist terrorists" Reuters