Iraqi Prime Minister Haider al-Abadi, who has been trying for months to replace the current cabinet, has accepted the resignations of five more ministers, his office said on Tuesday.

Abadi issued orders accepting the resignations of the ministers of oil, transport, housing and construction, water resources and industry, as well as interior, which had been previously announced.

But replacing them will be a major challenge: Abadi struggled to win parliament's approval for even relatively minor ministers, and oil and interior are two of the most powerful ministries in the country.

And while parliament finally approved a few of Abadi's candidates in late April, a court scrapped the session, from which some lawmakers were barred from attending, two months later.

The premier called in February for the cabinet to include technocrats, but has faced major opposition from powerful political parties that rely on control of ministries for patronage and funds.

Populist Shiite cleric Moqtada al-Sadr later took up the call for a technocratic government, and has organised repeated demonstrations calling for reforms.

His supporters have broken into Baghdad's fortified Green Zone area, where the government is headquartered, on multiple occasions during Friday protests.

Sadr called for a break in protests during the month of Ramadan, when observant Muslims fast from dawn to dusk, which ended two weeks ago.

The cleric urged his supporters to protest again last Friday, making a brief appearance himself in Baghdad's Tahrir Square as thousands of people defied government warnings against demonstrating.

The protest renews pressure on the government to carry out reforms, but demonstrations in the past year have ultimately resulted in little more than unfulfilled promises, as those in a position to effect change benefit from the existing system.