British Royal Air Force (RAF) fighter jets launched laser-guided bombs and missiles above Iraq on Saturday in aid of Kurdish forces who began an all-out ground offensive against the Islamic State (ISIS) terror group to liberate their terrified and oppressed population.

The Kurdish forces, backed by the U.S.-led airstrikes, eventually recaptured the northern Iraqi town of Sinjar from the ISIS, according to Reuters.

The fall of Sinjar from ISIS came as evidence grew that the jihadist group had suffered another major setback when a U.S. drone strike killed "Jihadi John," the infamous British ISIS executioner who had personally beheaded a number of American, British and other foreign hostages on video camera.

Kurdish Peshmerga troops initially captured the main road near the town that allowed them to cut off terrorist shipments of weaponry, food and drugs, said the Daily Express.

"ISIL (another acronym for Islamic State) defeated and on the run,'' the Kurdistan regional security council said in a tweet, according to Reuters.

The news agency said Kurdish forces, which entered Sinjar "from all directions,'' had secured Sinjar's wheat silo, cement factory, hospital and several other public buildings.

Britain's RAF jets also pounded key jihadi positions in the mountains of Sinjar, forcing the terror group to go on the run, according to the report.

A spokesman for the Ministry of Defence (MoD) said RAF Tornado jets and Reaper drones have flown a series of bombing and reconnaissance raids over northern Iraq in recent days in aid of Kurdish forces. Two Tornado jets that had taken off from RAF Akrotiri in Cyprus was also part of an international coalition aimed at destroying the "appalling terrorist organisation."

The recent development is considered one of the most significant counter-attacks since the militants swept through the north last year.

Iraqi Kurdish regional President Massaoid Barzani declared victory in an offensive that could provide critical momentum in efforts to capture the western provincial capital Ramadi, and Mosul in the north, an ISIS bastion, said Reuters.

"The Liberation of Sinjar will have a big impact on liberating Mosul,'' Barzani said.

Bombing campaigns by Russian jets have also severely weakened ISIS' grip on the region, allowing Kurdish forces to drive the jihadis backwards.

Sinjar is home to Iraq's Yazidi minority who suffered at the hands of ISIS when it overran the area in August 2014, systematically slaughtering, enslaving and raping thousands, said Reuters.

The number of Islamic State fighters in the town had reportedly risen to nearly 600 in the run-up to the offensive but only a handful were left in Sinjar on Friday.