An Iraqi operation to recapture the city of Mosul, the last stronghold of the so-called Islamic State (IS) in the country, has started.
Artillery began firing on the city early on Monday, in a long-awaited assault from Kurdish Peshmerga, Iraqi government and allied forces.
Tanks are now moving towards the city, which has been held by IS since 2014.
The UN has expressed “extreme concern” for the safety of up to 1.5 million people in the area.
Reports said, Kurdish forces east of Mosul, says tanks are advancing on the city, kicking up clouds of dust.
As the operation began, one Kurdish general told our correspondent: “If I am killed today I will die happy because I have done something for my people.”
Kurdish forces say they have retaken a number of villages in their advance.
Meanwhile pro-government forces are attacking from an airbase in Qayyarah, about 60km (37 miles) to the south, which was recaptured in August.
The US-led coalition fighting IS is backing the assault with air strikes, the operation is complex and analysts say it could last for weeks, if not months.
The recapture of the city, capital of the northern Nineveh governorate, would mark the effective defeat of IS in Iraq, officials say.
It was from Mosul 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.
The start of the operation was announced by Prime Minister Haider al-Abadi in a televised address in the early hours of Monday (local time), “The hour of victory has come,” he said.
“Today I declare the start of the heroic operations to liberate you from Daesh,” he said, using another name for IS.
“God willing we will meet in Mosul to celebrate the liberation and your salvation from Isis (IS) so we can live together once again, all religions united and together we shall defeat Daesh to rebuild this dear city of Mosul.”
Surrounded by senior Iraqi officers, the prime minister vowed that only government forces would enter Mosul, a Sunni-majority city.
This, analysts said, was an attempt to counter fears that the operation could turn into a sectarian conflict.
About 30,000 pro-government forces are involved in the operation. The main assault is being led by Iraqi army troops based south of Mosul.
About 4,000 Kurdish Peshmerga militia have begun clearing villages in the east.
Sunni tribal fighters and Shia-led paramilitary forces are also due to take part. Planes from the US-led coalition against IS are providing air support.
US Special Operations personnel are advising forces on the ground. Elite Iraqi counterterrorism forces are expected to join in the coming days.
An estimated 4,000-8,000 Islamic State fighters are defending the city.
The UN’s under-secretary for humanitarian affairs and emergency relief coordinator, Stephen O’Brien, asked for civilians to be protected and be given access to assistance “they are entitled to and deserve“.
“I am extremely concerned for the safety of up to 1.5 million people living in Mosul who may be impacted,” he said in statement.
As many as one million people could be forced to flee their homes because of the operation, he added.
There are no firm figures on how many people remain in Mosul, but there were more than two million there when IS took the city more than two years ago.