The Iraqi leader's trip to London, during which he also met King Charles III, focused on security, migration and infrastructure, with the two leaders agreeing a strategic "defence relationship" to deepen cooperation.

It comes more than 20 years after Britain took part in the US-led invasion which left the country reeling from conflict for years.

Starmer -- who entered Downing Street last July -- is eager to reset ties with a host of capitals, from Beijing to Brussels, and keen to seal any deals to boost Britain's ailing economy.

"The leaders reaffirmed their commitment to the vision of a prosperous, sovereign Iraq through a new partnership focused on trade and investment," a UK-Iraq joint statement said after Tuesday's meeting.

"The prime ministers signed a landmark Partnership & Cooperation Agreement (PCA), a wide-ranging treaty on trade and strategic cooperation and agreed a trade package worth up to pound12.3 billion," it added.

That is more than 10 times the total value of UK-Iraq bilateral trade last year.

It contained UK-led mega infrastructure projects such as removing mines across Iraq left after decades of war and unrest, water and sewerage improvements and desalination in areas such as southern Basra as well as interconnecting the Iraqi and Saudi power grids.

A desperate lack of fresh water due to drought and climate change and frequent power blackouts, especially in the summer, have been major sources of discontent among the Iraqi population.

- Migration focus -

The three-day visit comes amid a complicated situation in the Middle East fuelled by the Gaza war between Israel and Hamas, as well as a fragile ceasefire in Lebanon between Israel and the Lebanese pro-Iranian militant group Hezbollah.

Donald Trump's move back into the White House next week, and expectations he will resume his hardline stance towards Iran, also loom large over the region's geopolitics.

Oil-rich Iraq, which is an ally of Iran as well as a strategic partner for Washington, has for decades practised a delicate balancing act, while also seeking to deepen its ties to wealthy Gulf countries.

Sudani -- brought to power in 2022 by a coalition of pro-Iran parties -- met Iran's supreme leader Ayatollah Ali Khamenei as recently as last week.

Starmer and Sudani also agreed on the principles for the return of Iraqi irregular migrants in the UK and discussed the next practical steps, the joint statement said.

Coinciding with Sudani's visit, Britain's National Crime Agency announced the arrest of three men suspected of smuggling migrants from the Kurdistan Region of Iraq (KRI) to Britain, in a "ground-breaking" joint operation.

Involving the Kurdistan Region Security Council and Kurdistan Region Security Agency, those detained are allegedly linked to a smuggling network run by a UK-based facilitator jailed for 17 years last November.

Migration -- regular and irregular -- is a key issue for Starmer as he faces domestic pressure to curb arrivals.

The number of migrants arriving in Britain on small boats after crossing the English Channel soared to over 36,800 in 2024, according to official data.

At least 76 deaths were recorded, making it the deadliest year for migrants who are taking ever greater risks to evade Britain's border controls.

- Border security -

Both leaders "agreed that the increasingly global nature of organised immigration crime underscores the need to stop people smuggling gangs from putting so many lives at risk", their statement said.

"Strengthening the border security of our nations is a key part of this effort," it added.

The pound12.3 billion package also included the reconstruction of the Al-Qayyarah airbase.

Sudani likewise met with business leaders including from oil giant BP, which recently announced long-term investment in Iraq.

Tuesday's talks come as Sudani said his country was preparing for the end of the military presence in Iraq of the Global Coalition to Defeat ISIS.

The United States maintains about 2,500 troops in Iraq and 900 more in Syria seeking to prevent any resurgence of the Islamic State jihadist group.

President Joe Biden's administration has agreed with Iraq to end the coalition's role by September 2025, but stopped short of a complete withdrawal of US forces, whose presence has been opposed by Iran-aligned armed groups in Iraq.

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