The office of Prime Minister Mohamed Shia al-Sudani issued a photograph of the head of government with top-ranking officials both of the Iraqi armed forces and of the international coalition set up by Washington to fight the Islamic State (IS) jihadist group.

Sudani "is hosting the start of the first round of bilateral dialogue between Iraq and the US to end the mission of the international coalition in Iraq," the office said in a statement.

"The talks and whatever progress made will determine the length of these negotiations," Sudani's foreign affairs adviser, Farhad Alaaldin, told AFP.

"Iraq is engaging the other countries taking part in the international coalition for bilateral agreements that serves the best interest of Iraq and these countries."

Washington had said on Thursday that it had agreed with Baghdad on the launch of "expert working groups of military and defence professionals" as part of the Higher Military Commission set up in agreement with Baghdad.

The working groups would examine "three key factors", Washington said: "the threat from ISIS, operational and environmental requirements and the Iraqi Security Forces' capability levels."

Pentagon deputy press secretary Sabrina Singh acknowledged that the US military footprint in Iraq "will certainly be part of the conversations as it goes forward", indicating that Baghdad's desire for a reduction in these forces is on the table.

For Iraq's foreign ministry, the aim would eventually lead to formulating "a specific and clear timeline... and to begin the gradual reduction of its (the coalition's) advisers on Iraqi soil".

The talks -- which have been planned for months -- come at a time of heightened tensions in Iraq and the region linked to the war between Israel and Hamas, which has sparked a surge in attacks on American and other coalition forces.

There have been more than 150 attacks targeting coalition troops since mid-October, many of them claimed by the Islamic Resistance in Iraq, a loose alliance of Iran-linked groups that oppose US support for Israel in the Gaza conflict.

There are roughly 2,500 US troops deployed in Iraq and about 900 in Syria as part of the anti-IS coalition formed in 2014 -- the year the jihadist group overran around a third of Iraq.