BAGHDAD (Reuters) - Iraq’s parliament approved on Monday two more ministers in Prime Minister Adel Abdul Mahdi’s cabinet but political divisions blocked his attempts to form a complete government as the defense, interior, and justice portfolios remain empty.

Intensifying disagreements between the rival Islah and Bina blocs, led by populist Shi’ite cleric Moqtada al-Sadr and Iran-backed militia leader Hadi al-Amiri, have prevented the formation of a full government of 22 ministers.

Lawmakers were scheduled to vote on the final five remaining empty posts but managed only to approve Shaima Khalil as education minister and Nawfal Moussa as migration minister before the session descended into chaos.

Abdul Mahdi was confirmed as premier in October after months of political gridlock that followed an inconclusive May election. He was sworn in with only a partial cabinet and has since been trying to get a full government up and running.

The post of interior minister has emerged as the biggest stumbling block over which parliament’s two biggest coalitions are arguing.

Amiri’s bloc has repeatedly nominated Falih Fayadh, who once led the umbrella grouping of militias known as the Popular Mobilisation Forces. Sadr’s coalition has consistently rejected him.

Lawmakers allied with Sadr walked out of Monday’s session when Speaker Mohammed al-Halbousi put forth Fayadh’s name for a vote, as they have done several times in the last few months, thus breaking quorum and ending the session. Halbousi said he would ask Abdul Mahdi to put forward a different name next time.

“We walked out of the session because we strongly reject holding a vote on Falih Fayadh as interior minister. We will never show leniency and our position is firm. No vote for partisan candidates,” said lawmaker Jamal Fakhir.

The deadlock over forming a cabinet has raised the prospect of further unrest as the country struggles to rebuild and recover after three years of war with Islamic State.

The prime minister faces the daunting task of rebuilding much of the country after that war, solving acute economic problems and coping with power and water shortages.