Philippine President Rodrigo Duterte declared martial rule in Mindanao province on Tuesday after violent clashes broke out between authorities and militants linked with the self-proclaimed "Islamic State" group (IS), leaving at least one police officer dead.

The president's spokesman made the announcement from Moscow, where Duterte was on an official visit. The country's constitution limits martial law periods to 60 days, but Duterte later said it could last up to year.

Duterte cut short his trip following an outbreak of violence.

The bloodshed began when police and soldiers raided an apartment in the southern city of Marawi where Isnilon Hapilon, an alleged leader of the notorious Abu Sayyaf gang and the Philippine head of IS, was suspected of hiding. The raid set off clashes around the city, with military chief of staff General Eduardo Ano telling broadcaster CNN Philippines that there were an estimated 50 gunmen.

Images posted on social media showed masked militants prowling the city streets and setting fire to buildings, including the municipal jail and a school. The militants, who are suspected of belonging to Abu Sayyaf and another group, Maute, also reportedly seized a hospital amid the fighting.

Abu Sayyaf, an extremist group based in the southwestern part of the Philippines, has been carrying out bombings, ransom kidnapping and beheadings for more than four decades. Maute is one of several new groups in the country that has pledged allegiance to IS.

Major offensive

Under Duterte, the government of the Philippines has undertaken a major offensive against both Maute and Abu Sayyaf. The latter is labeled a terrorist organization by both Manila and Washington.

Last month, government forces killed dozens of Maute militants and captured a jungle camp belonging to them, where they found bombs and other weapons, along with passports belonging to suspected Indonesian militants.

At the end of April, marines killed a high-ranking Abu Sayyaf leader named Alhabsy Misaya, blamed for the kidnapping of dozens of Indonesian, Vietnamese and Malaysian nationals.

The military also recently foiled a mass kidnapping plot by Abu Sayyaf on the resort island of Bohol.

The fighting in Marawi also came shortly after the US and other Western governments warned that terrorists were planning a string of kidnappings in tourist hotspots across the country.

Similar to Marcos's dictatorship

Duterte told citizens in a video address that he would be "harsh" in dealing with terrorism, saying it was one of his election campaign promises last year.

"What I told everyone, do not force my hand into it. I have to do it to preserve the Republic of the Philippines, the Filipino people," he said.

He vowed the crackdown would be similar to the late Ferdinand Marcos's dictatorship.

 "It could not be any different from what President Marcos did," he said in the video. Marcos presidency ended with a "People Power" revolution in 1986.

Russian weapons

Duterte said he was relying on an arms deal with Moscow to provide advanced weaponry for the fight, according to Russian media. Duterte told Russian President Vladimir Putin his country was not properly equipped to fight IS.

Before the trip Duterte had said he planned to pursue deals to buy Russian helicopters and warplanes. 

blc/se (AFP, AP, dpa)