Forces operating in Mosul theatre

A wide array of Iraqi and international forces are involved in the fight to retake Mosul from the Islamic State jihadist group, which overran the country's second city in 2014.

Prime Minister Haider al-Abadi announced the launch of the much-awaited operation on Monday and anti-IS forces have already retaken several villages and significant swathes of land from the jihadists.

These are the main forces that are operating in the wider Mosul theatre or may do so. Not all will play a role in the fighting inside the city:

Islamic State group

Heavily armed jihadists who have had years to prepare their defences in Mosul, which IS seized before sweeping through cities and towns to the south in 2014.

Counter-terrorism service

Iraq's elite force which have spearheaded most key battles against IS. But constant reliance on these troops over the past two years has taken a toll.

Army

The Iraqi army has begun playing a more successful role in operations against the jihadists since it was revitalised by US-led training after several of its divisions collapsed during the IS offensive two years ago.

Police

Includes special forces units, paramilitary federal police and provincial police. Many Iraqi police forces have played roles more akin to those of soldiers in the war against IS.

US-led coalition

A US-led international alliance is carrying out air strikes against IS in Iraq and Syria, and providing training, arms and equipment to forces opposing the jihadists.

There are more than 7,500 coalition military personnel deployed in Iraq, over half of them from the United States.

Most are in advisory or training roles, but special forces soldiers who have fought the jihadists on the ground have been deployed and coalition forces near Mosul have also targeted IS with artillery.

Kurdish forces

The peshmerga are the armed forces of Iraq's autonomous Kurdish region. They nominally answer to the federal government but in practice operate independently, battling IS along a long front in the country's north.

Forces from Iran's Kurdistan Freedom Party (PAK) are embedded in some peshmerga operations. It is separate from other Iranian Kurdish rebels groups that have also been active on the Iraqi side of the border such as the Kurdistan Democratic Party of Iran (KDPI) and the Party of Free Life of Kurdistan (PJAK).

Hashed al-Shaabi

An umbrella organisation created in 2014, which includes a dizzying array of paramilitary forces who vary widely in skill and in the degree to which they are actually under government control.

The main groups are Iranian-backed Shiite militias, including Ketaeb Hezbollah, Asaib Ahl al-Haq and Badr. The Hashed has played a major role in the anti-IS fight in Iraq but forces within it have also carried out abuses.

It includes recently trained Sunni tribal forces sometimes referred to as "tribal mobilisation" or "national mobilisation".

Iranian advisers

Iranian forces have provided advice and other assistance, including funding for various militias fighting IS in Iraq.

Qassem Soleimani, the commander of Iran's Revolutionary Guards foreign operations wing, has been repeatedly pictured in Iraq during the war.

Turkish troops

Deployed at a base near Mosul from which they have carried out artillery strikes against IS. Turkish troops are also present inside Iraq's autonomous Kurdish region.

The federal government has demanded their withdrawal, with the prime minister vowing that they will not take part in the operation to recapture Mosul, but Turkey has declined to do so.