Zebari, 68, who served as foreign minister for a decade after the 2003 US-led invasion that toppled dictator Saddam Hussein, had already been suspended temporarily from the contest on February 6, the eve of the scheduled presidential vote in parliament. He was one of two frontrunner candidates.

Postponement of that vote exacerbates war-scarred Iraq's political uncertainty because the president -- a largely ceremonial post -- names a prime minister from the largest bloc in parliament. Months after legislative elections, the head of government still hasn't been named.

Following the court's decision, Zebari on Sunday protested what he called an "injustice" based on a political decision to keep him out of the race, and stressed his innocence.

"Our behaviour and good conduct are cleaner and purer than the snow on Iraq's highest summit," he told a news conference.

Iraq's highest judicial body made its ruling after MPs submitted a complaint against Zebari. The complaint said his participation would have been "unconstitutional" because of the outstanding corruption charges, leaving him without the required "good reputation and integrity."

"The federal court decided in its verdict to invalidate the candidacy of Hoshyar Zebari to the post of president of the republic," state news agency INA announced.

- Controversial history -

The February 7 voting session was not held due to lack of a quorum after several political blocs and parties announced boycotts -- against the backdrop of competing claims to a parliamentary majority.

Zebari was initially tipped as a favourite, along with incumbent President Barham Saleh, out of a total of roughly 25 candidates.

The complainants to the court cited Zebari's 2016 dismissal from the post of finance minister by parliament "over charges linked to financial and administrative corruption".

Public funds worth $1.8 million were allegedly diverted to pay for airline tickets for his personal security detail.

The complaint also cited at least two other judicial cases linked to Zebari.

"I have not been convicted in any court," Zebari said in an earlier television interview, as the charges resurfaced on the eve of the scheduled parliamentary vote, alongside forecasts that he would unseat Saleh for the four-year posting.

On Tuesday, parliament announced the reopening of registration for presidential candidates, a post reserved for Iraq's Kurds.

Zebari said Sunday that his movement, the Kurdistan Democratic Party which runs the autonomous Kurdish region in northern Iraq, does not for the moment have an alternative candidate.

Controversially, Zebari was a keen supporter of Iraqi Kurdistan's ill-fated 2017 referendum on independence which sparked a crisis between Baghdad and the KDP, almost resulting in bloodshed between the two camps.

Iraqi politics have been in turmoil since general elections were held in October. The polls were marred by a record-low turnout, post-election threats and violence, and a delay of months until final results were confirmed.

Intense negotiations among political groups have since failed to form a majority parliamentary coalition to name a new prime minister to succeed Mustafa al-Kadhemi.