An Iraqi court has dealt a blow to Prime Minister Haider al-Abadi's efforts to replace a cabinet dominated by entrenched political parties, invalidating the session that approved new ministers.

But it also settled the issue of whether parliament speaker Salim al-Juburi retains his job -- a question that had resulted in two rival claimants to the position -- by scrapping another session at which lawmakers voted to sack him.

The sessions were held during a chaotic month for Iraqi politics in which lawmakers failed to approve all but a handful of new ministers proposed by Abadi, angering protesters who eventually stormed parliament.

With the ruling, the court effectively turns back the Iraqi political clock to the pre-April status quo: no new ministers have been approved, and Juburi is confirmed in his position.

"The federal court decided to invalidate the parliamentary sessions of April 14 and 26," higher judicial council spokesman Abdelsattar Bayraqdar said in a statement on Tuesday.

The first session, at which lawmakers voted to sack Juburi, lacked the necessary quorum, with only 131 MPs present, a judicial official said.

The second, in which lawmakers voted to accept some of Abadi's cabinet nominees, took place in an atmosphere "inconsistent with freedom of opinion" as guards entered the session and some MPs were prevented from attending, the official said.

Abadi has pushed for Iraq's current party-affiliated cabinet to be replaced by technocrats, but has faced significant opposition from powerful political forces that rely on control of ministries for patronage and funds.

Shiite cleric Moqtada al-Sadr organised demonstrations calling for a government of technocrats, and his supporters have breached the fortified Green Zone area, where the government is headquartered, multiple times in recent months.

Sadr halted the protests for the holy Muslim fasting month of Ramadan, but has called for a major demonstration after it ends next week, which will increase pressure for the fractious parliament to take action.

The political chaos has paralysed parliament at a time when Iraq faces a slew of challenges, including a war against the Islamic State jihadist group, an economic crisis caused by slumping oil prices, and abysmal public services that have long angered citizens.