The resident from Manbij, a Syrian city held by ISIS for more than two years, said militants would brutally punish people who resisted their vile way of life.

The man, who wished to remain anonymous out of fear of reprisal, told BBC Newsnight: “After they beheaded someone, they would crucify his body.

“They would leave it to rot for two days.

“If they caught you smoking, they would probably cut some fingers off.

He added: “If they caught you stealing and there were two witnesses, then that was it.

“They threw people from the top of buildings.”

Last year, before the city was liberated, it was reported that a man was thrown off a building for allegedly being gay.

Hundreds were ordered to watch the vile punishment including children as he fell 100ft while blindfolded with hands bound behind his back.