He says “if I think that ISIS has taken a foothold also in Luzon,” the main northern island, “and terrorism is not really far behind, I might declare martial law throughout the country.”

Duterte also said that militants who stormed southern Marawi city beheaded the local police chief at a checkpoint they set up.

Duterte spoke to reporters after returning from a visit to Moscow as fighting raged in Marawi between government troops and Muslim militants who took about a dozen people hostage. He has earlier declared martial law in the southern Mindanao region, where Marawi is located.

Duterte warned martial law would be similar to military rule imposed by dictator Ferdinand Marcos a generation ago.

Marcos’s two-decade rule ended in 1986 when millions of people took to the streets in a famous “People Power” revolution.

“Martial law of Mr Marcos was very good,” Duterte said.