The militant group Isis is “failing and disintegrating”, the Foreign Secretary has said, as Iraqi and Kurdish troops advance on the occupied city of Mosul.

Boris Johnson told the House of Commons that the group was being “routed on the battlefield”, and that half of its former territory in Iraq and a quarter in Syria had been recaptured.

“Daesh’s defeats on the battlefield are helping to counter its ideological narrative,” Mr Johnson said.

“As one defeat succeeds another they are increasingly being seen for what they are – a failing and disintegrating movement.”

The minister said Iraqi and Kurdish forces had now reached the outskirts of Mosul itself, partly with the help of Coalition, including British, air power.

The allied forces attacked the city, which has been held by Isis for two years, on three fronts, starting in mid-October.

The Foreign Secretary however sounded a note of caution, adding: “In some areas Daesh have mounted fierce resistance, dispatching scores of suicide bombers.

“The House can be sure that Daesh will be driven from Mosul, but this is the toughest task that Iraq’s security forces have yet encountered and success will take time.”

Emily Thornberry, Labour's shadow foreign secretary, agreed that Isis was "a movement that is embattled, weakened, and in retreat".

In pictures: Civilians freed from Isis in Manbij Show all 11 1 /11 In pictures: Civilians freed from Isis in Manbij In pictures: Civilians freed from Isis in Manbij Women and children celebrating after being freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A man cuts the beard of a civilian who was freed from Isis by the SDF in Manbij on 12 August Reuters In pictures: Civilians freed from Isis in Manbij Women carry newborn babies while running after being freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A woman freed from Isis hugs an SDF fighter in Manbij on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A woman adding her veil to a pile of niqabs burning in Manbij, Syria, after being freed from Isis on 12 August Reuters In pictures: Civilians freed from Isis in Manbij Children celebrating on top of a lorry after being freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A man and child freed from Isis by the SDF in Manbij on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A woman carrying her children walks towards SDF fighters after being freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij A woman and child freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij An SDF fighter kisses a crying man who was freed from Isis in Manbij, Syria, on 12 August Reuters In pictures: Civilians freed from Isis in Manbij Hundreds of civilians freed from Isis in Manbij, Syria, on 12 August Reuters

Mr Johnson also used his statement to call on Russia to end the bombing of civilians in the Syrian city of Aleppo, where it has been accused of committing war crimes.

“This House should be in no doubt that the attack on eastern Aleppo has little do with defeating terrorism and everything to do with preserving Assad’s blood-soaked regime,” he said.

“Wherever Daesh has lost ground in Syria this has frequently owed nothing to Assad or his backers. In August it was the Syrian democratic forces that threw Daesh out of the town of Manbij.”