A crack unit has been formed to hunt down the terror chief whose barbaric Islamic State group has blazed a trail of murder and mayhem across the Middle East .

Around 100 CIA spooks and special forces are hunting for 42-year-old Abu Bakr al-Baghdadi, dubbed The Ghost because he leaves no trace despite running an army of followers.

It is the biggest counter-terror search since the Americans tracked down and killed al-Qaeda mastermind Osama bin Laden in 2011.

Using unmanned spy planes, other aircraft and satellite imagery, intelligence experts are gathering mobile phone call data and movements on the ground in Iraq and Syria .

A source said: “Al-Baghdadi is elusive but he will be found eventually.

“His forces are stretched so phone calls will be made – that will be his weak point.”

Al-Baghdadi’s 25,000-strong army has conquered territory – something al-Qaeda never managed – and slaughtered thousands as it seeks to establish an Islamist caliphate in Syria and Iraq.

Britain is increasing the amount of help in the fight against the Islamic State.

Last week troops were flown to Kurdish capital Ibril on a secret mission to help refugees, which was later aborted.

And British spy planes are collecting intelligence on the movement of jihadists to be shared with Kurdish and Iraqi security forces and the US military.

Defence Secretary Michael Fallon hinted that British troops could be involved in combat.

He said: “We can’t tell exactly how this is going to unfold. This is not simply a humanitarian mission.”

Back home, pressure mounted on Prime Minister David Cameron as Church leaders savaged him in a damning letter to Downing Street.

The Bishop of Leeds, the Rt Rev Nicholas Baines, slammed the “lack of coherent response” from Britain to the spread of the Islamic State.

His letter – backed by the Archbishop of Canterbury, Justin Welby – also attacked the PM’s “silence” over helping Christians in Iraq.

Mr Cameron responded: “If we do not act to stem the onslaught of this dangerous terrorist movement, it will only grow stronger until it can target us on the streets of Britain.”