Has ISIS forced this Catholic priest to convert to Islam in the Philippines?

Speculation is mounting as to whether a Catholic priest abducted by an ISIS-linked militants in the Philippines was forced to convert to Islam.

Jihadist fighters seized the town in May with thousands either killed, captured or used as sex slaves with the Philippino-ISIS affiliate following similar tactics to their partners in the Middle East.

ReutersMembers of Philippine Marines aboard a vehicle as more soldiers reinforce to fight the Maute-ISIS group in Marawi City in southern Philippines.

Among the hostages was Father Teresito Soganub, a leading church figure, who was rescued early on Sunday after being found near a mosque following a prolonged campaign by government forces.

Other hostages who escaped or were rescued said the Maute-ISIS group forced them to convert to Islam, cook food and carry wounded fighters while some women were forced to marry jihadists.

Zia Alonto Adiong, spokesman for the provincial crisis management committee, said Soganub had also been forced to convert to Islam, according to local media reports.

But the local Marawi Bishop Edwin dela Pena denied having any confirmation of Soganub's conversion, adding if someone is forced to change religion 'you cannot consider that full conversion'.

He told reporters: 'There is no substance to it if you are under duress. You cannot give your full consent. That is what religion is all about.

'Whatever it is, true or not, it doesn't hold water for me,' the bishop added.

He added: 'We have not abandoned him. We continue to pray for him.'

Soganub is expected to meet Philippine President Rodrigo Duterte after receiving medical treatment, according to the Sydney Morning Herald.

It comes after a major military offensive to recapture the city, held by the Islamists since May.

'We are trying to convince them to release all their hostages – if not all the hostages, just the women inside the main battle area,' said Colonel Romeo Brawner, the deputy commander of a Marawi taskforce.

'If they surrender we will not shoot them. That's our arrangement,' he said.

But despite promising victory was days away for several weeks, the Philippines military have been resisted by the jihadists holding out against the seige and prompting fears of the extremists gaining a foothold in the region.