Islamist gunmen who took a Catholic priest and churchgoers hostage in the Philippines have beheaded the city's local police chief, President Rodrigo Duterte has said.

Members of the ISIS-inspired Maute Islamist group stormed the Cathedral of Our Lady Help, in Marawi city on Mindanao island, and abducted church staff including Father Chito Suganob and worshipers.

'They have threatened to kill the hostages if the government forces unleashed against them are not recalled,' Filipino Archbishop Socrates Villegas said in a statement.

President Duterte, who declared martial law in parts of Mindanao after militants clashed with soldiers in Marawi yesterday, says he may extend it to other parts of the country if extremists seek sanctuary elsewhere.

Chilling photographs from Marawi City in the Philippines, where an Islamist group has taken a priest hostage, show militants planting the ISIS flag on top of buildings

Several online posts appeared to show the black and white flag used by ISIS hung from buildings in Marawi

Islamist gunmen have taken hostages including a Catholic priest in Marawi, Philippines, shortly after President Rodrigo Duterte declared martial law to combat extremism. Pictured: Troops evacuating people from Marawi

Members of the ISIS-inspired Maute Islamist group stormed the Cathedral of Our Lady Help, on Mindanao island (pictured)

Duterte (pictured) declared martial law across the southern region of Mindanao last night after Islamist militants rampaged through the city of Marawi

'We are in state of emergency,' he told reporters in Manila after a state visit to Moscow, adding he would deal with militants 'harshly'.

Chilling photos on social media purported to show Maute gunmen planting an ISIS-style black and white flag on top of a building in the middle of the city.

'At the time of his capture, Father Chito was in the performance of his ministry as a priest,' Archbishop Villegas said.

'He was not a combatant. He was not bearing arms. He was a threat to none. His capture and that of his companions violates every norm of civilised conflict.'

But Marawi Mayor Majul Usman Gandamra has refused to confirm reports the terror group took hostages and insisted that the local government has the situation under control.

In a telephone interview with national broadcaster ANC, Gandamra said he was working with the military to bring peace and order to the city.

Police and military spokesmen were not immediately available to comment on Villegas's report of the hostage taking.

Filipino Archbishop Socrates Villegas said the extremists have threatened to kill the hostages if the government forces unleashed against them are not recalled

Archbishop Villegas went on to say the extremists took an undisclosed number of hostages to a secret location and the abductees have not been heard from since

'He was not a combatant,' said Archbishop Villegas. 'He was not bearing arms. He was a threat to none. His capture and that of his companions violates every norm of civilised conflict'

But Marawi Mayor Majul Usman Gandamra has refused to confirm reports the terror group took hostages in Marawi

The fighting in Marawi erupted yesterday when security forces raided a house they believed Isnilon Hapilon, leader of the infamous Abu Sayyaf kidnap gang

More than 100 gunmen responded to the raid by burning buildings and conducting other diversionary tactics

President Duterte says he may extend it to other parts of the country if extremists seek sanctuary elsewhere

The fighting in Marawi erupted yesterday when security forces raided a house they believed Isnilon Hapilon, leader of the infamous Abu Sayyaf kidnap gang and Philippine head of ISIS, was hiding.

WHAT HAPPENS UNDER MARTIAL LAW? Martial law allows the president to 'call out the armed forces to prevent or suppress lawless violence, invasion or rebellion', according to the constitution. Defence Secretary Delfin Lorenzana said security forces would be able to arrest suspected militants and hold them for three days without charge. During the nine years of martial law under former dictator Ferdinand Marcos, police and troops tortured, abducted and killed thousands of people who were critical of the dictatorship, according to rights groups and historians. Duterte said his version of martial law would be 'harsh' and similar to that under Marcos. Advertisement

The United States regards Hapilon as one of the world's most dangerous terrorists, offering a bounty of $5million for his capture.

More than 100 gunmen responded to the raid by burning buildings and conducting other diversionary tactics, according to Defence Secretary Delfin Lorenzana.

Security analysts say Hapilon has been trying to unite Filipino militant groups that have professed allegiance to IS.

These include the Maute group, named after two brothers who lead it and which is based near Marawi.

Duterte had repeatedly said the growing influence of Islamic State was one of the nation's top security concerns, and martial law was necessary to stop it.

However Islamist militancy is not new to the southern Philippines, where a decades-long Muslim separatist insurgency claimed more than 120,000 lives.

Muslim rebels orchestrated a siege in the southern city of Zamboanga in 2013 that left more than 200 people dead.

Duterte had repeatedly said the growing influence of Islamic State was one of the nation's top security concerns

Islamist militancy is not new to the southern Philippines, where a decades-long Muslim separatist insurgency claimed more than 120,000 lives

Martial law allows the president to 'call out the armed forces to prevent or suppress lawless violence, invasion or rebellion', according to the Filipino constitution

ISIS KILLS FIVE IN FIRST SUICIDE ATTACK IN SOMALIA ISIS has claimed responsibility for its first ever suicide attack in the troubled African nation of Somalia. Police said five people were killed when a suicide bomber blew himself up at a checkpoint in the north-eastern port city of Bosaso, in Puntland, today. Witnesses told of how the blast occurred near a hotel often used as a meeting place for local officials. 'I think the bomber was trying to target the hotel but he was stopped at the checkpoint close to the hotel and he decided to detonate his explosives,' said witness Awke Mohamed. Puntland, which set up its own government in 1998, often comes under attack from Al-Qaeda-linked Shabaab militants. It is also home to a breakaway group of fighters who have declared allegiance to ISIS - but failed to gather much support. Advertisement

But the government of then-president Benigno Aquino did not declare martial law.

Aquino also said he had considered imposing martial law just before standing down last year in Sulu, island strongholds of the Abu Sayyaf in the far south of Mindanao.

But Aquino said he decided against it partly because military rule could spark resentment among local people.