The agreement to be signed with UK Prime Minister Keir Starmer will consolidate cooperation between Britain and Iraq and will be "one of the most important steps in relations between Iraq and the United Kingdom", Sudani told AFP during the flight from Baghdad.

The Iraqi prime minister's visit, during which he will also meet King Charles III, comes more than 20 years after Britain took part in the US-led invasion of Iraq.

Sudani's trip would give "momentum" to the "historic" new relationship between the two countries, he told AFP.

He said there would also be a joint statement on bilateral security cooperation, referring to the new "arrangements" his country was planning ahead of the end of the military presence in Iraq of the Global Coalition to Defeat ISIS.

The US maintains about 2,500 troops in Iraq and 900 more in Syria as part of the campaign to prevent resurgence of the Islamic State (IS) jihadist group, also known as ISIS.

President Joe Biden's administration has agreed with Iraq to end the coalition's presence by September but stopped short of a complete withdrawal of the US forces, whose presence has been opposed by Iran-aligned armed groups in Iraq.