The UN chief's visit, his first to Iraq in six years, comes as the war-torn country prepares to mark the 20th anniversary of the toppling of longtime dictator Saddam Hussein in a US-led invasion.

Guterres said he wanted to demonstrate "solidarity with the people and the democratic institutions of Iraq and a solidarity that means that the United Nations is totally committed to support the consolidation of the institutions in this country".

He said he also wanted to express his "confidence that Iraqis will be able to overcome the difficulties and challenges they still face through an open and inclusive dialogue".

Guterres, who arrived late Tuesday, is due to hold talks with Foreign Minister Fuad Hussein, before meeting Prime Minister Mohammed Shia al-Sudani, President Abdel Latif Rashid and parliament speaker Mohammed al-Halbusi, the foreign ministry said.

The three leaders are respectively Iraq's top Shiite, Kurdish and Sunni Arab officials under the sectarian power-sharing system established after the US-led invasion toppled Saddam's Sunni Arab-dominated regime.

Guterres will also meet representatives of women's and youth rights groups.

On Thursday, he will visit a camp for displaced people in the north of the country, before heading to Kurdistan regional capital Arbil for talks with Kurdish officials.

He will then travel on to Qatar, where he will attend the summit of the Least Developed Countries.

The UN chief's last visit to Iraq was in spring 2017.