An investigating judge in Baghdad has "issued arrest warrants for four senior officials of the former government", the government's anti-corruption agency said in a statement.

The four men, who include a former finance minister and staff members of former prime minister Mustafa al-Kadhemi, are all living outside the country, according to an official at the agency who spoke on condition of anonymity.

The warrants do not name any of the officials, but according to the official, they are former finance minister Ali Allawi, the director of cabinet Raed Jouhi, personal secretary Ahmed Najati, and adviser Mushrik Abbas.

Allawi, a respected politician and academic, resigned in August last year. When the scandal broke a few months later, he denied all responsibility.

Al-Kadhemi defended his record on fighting corruption, saying his government had discovered the case, launched an investigation and taken legal action.

The case, which has been dubbed "the heist of the century", sparked outrage in oil-rich Iraq, which critics say is plagued by corruption.

At least $2.5 billion was stolen between September 2021 and August 2022 through 247 cheques that were cashed by five companies. The money was then withdrawn in cash from the accounts of these companies, most of whose owners are on the run.

The four men are accused of "facilitating the embezzlement of sums belonging to the tax authorities," the statement said, adding that they would also be subject to an asset freeze.

The country's current Prime Minister Mohammed Shia al-Sudani has vowed to crack down on corruption since his appointment in late October.