At the beginning of the battle that has raged for the past 12 days in Marawi City at the southern end of the Philippines, dozens of Islamist militants stormed its prison, overwhelming the guards.

"They said 'surrender the Christians,' " said Faridah P. Ali, an assistant director of the regional prison authority. "We only had one Christian staff member so we put him with the inmates so he wouldn't be noticed," he said.

Fighters from the Maute group, which has pledged allegiance to Islamic State (IS), menaced the guards and shouted at prisoners: but no one gave up the Christian man. "When they freed the inmates, he got free," said Ali.