United States President Donald Trump warned Iraq against picking Nouri al-Maliki as its prime minister on Tuesday, saying the US would no longer help the Middle Eastern country.

"I'm hearing that the Great Country of Iraq might make a very bad choice by reinstalling Nouri al-Maliki as Prime Minister," Trump wrote on Truth Social.

"Last time Maliki was in power, the Country descended into poverty and total chaos. That should not be allowed to happen again. Because of his insane policies and ideologies, if elected, the United States of America will no longer help Iraq," Trump wrote.

He added that the country, without US help, would have "zero" chance of success.

Trump campaigning to curb Iranian regime influence

Trump's comments are the starkest example yet of the president's campaign to curb Iran-linked groups' influence in Iraq, which has long walked a tightrope between its two closest allies, Washington and Tehran.

Reuters was not able to immediately reach Maliki for comment.

His warning comes days after the alliance of Shi'ite political blocs that hold a majority in Iraq's parliament picked Maliki, who previously served two terms as the country's prime minister, for the post.

As part of Trump's pressure campaign, Washington has also threatened senior Iraqi politicians with US sanctions targeting the Iraqi state should armed groups backed by Iran be included in the next government, Reuters reported last week.

Maliki is a senior figure in the Shi'ite Islamist Dawa Party. His tenure as Iraq's prime minister from 2006 to 2014 was a period marked by sectarian violence, a power struggle with Sunni and Kurdish rivals, and growing tensions with the US

He stepped down after the Islamic State seized large parts of the country in 2014, but has remained an influential political player, leading the State of Law coalition and maintaining close ties with Iran-backed factions.