A military operation to recapture the Iraqi city of Mosul from so-called Islamic State (IS) has begun, Prime Minister Haider al-Abadi says.

The long-awaited assault from Kurdish Peshmerga, Iraqi government and allied forces is backed by the US-led coalition fighting IS in Iraq.

Mosul, Iraq’s second largest city, has been under IS control since June 2014.

The UN has warned that the humanitarian impact could be “enormous”, and affect up to 1.2 million people.

Mosul is the group’s last major stronghold in Iraq. The loss of the city, officials say, would mark the effective defeat of IS in the country.

In an address broadcast on state television in the early hours of Monday, Mr Abadi said: “The hour has come and the moment of great victory is near.”

“Today I declare the start of these victorious operations to free you from the violence and terrorism of Daesh,” he added, using another name for IS.

Dressed in military uniform and surrounded by Iraqi officers, he vowed that only government forces would enter Mosul, a Sunni-majority city.

It was from there that IS leader Abu Bakr al-Baghdadi declared a caliphate – a state governed in accordance with Islamic law – in territory controlled by the group in Iraq and Syria.

An operation to retake the city, capital of the northern Nineveh governorate, has been planned for months.