Iraqi Prime Minister Haider al-Abadi declared victory in the 'liberated' city of Mosul today, his office said, in the biggest defeat yet for the Islamic State group.

Abadi 'arrives in the liberated city of Mosul and congratulates the heroic fighters and the Iraqi people on the achievement of the major victory', his office said in a statement.

The announcement comes after a gruelling nearly nine- month battle to retake the northern city from the jihadists after three years under their rule.

A photo on Abadi's official Twitter account showed him dressed in a black military uniform and cap as he arrived in Mosul to announce the recapture of the city.

However, the fighting did not seem to be completely over yet, with gunfire still audible in Mosul and air strikes hitting the city around the time the premier's office released the statement.

The recapture of Mosul will not however mark the end of the threat posed by IS, which holds territory elsewhere in Iraq and is able to carry out frequent bombings in government-held areas. -- Agencies