Iraqi Prime Minister Haider al-Abadi announced the removal of 11 of 33 cabinet posts Sunday, the first concrete step in a reform drive to curb corruption and streamline the government.

The announcement came as parliament and Abadi made preliminary moves toward holding top officials -- including ex-premier Nuri al-Maliki -- accountable for military disasters in the cities of Mosul and Ramadi, which have been seized by the Islamic State jihadist group.

Abadi rolled out a reform programme a week ago in response to popular pressure from weeks of protests against corruption and poor services, and to a call for drastic change from Iraq's top Shiite cleric, Grand Ayatollah Ali al-Sistani.

Parliament approved Abadi's plan along with additional measures two days later, but a major gap remains between announcements and implementation.

In a first move from proposals to action, Abadi scrapped three deputy premier positions, three ministries and a minister without portfolio, and merged four more ministries with others, his office said Sunday.

It is unclear whether the scrapped ministries -- human rights and the ministries of state for women's affairs and for provincial and parliamentary affairs -- will continue in another form, or will be done away with altogether.

Amid a major heatwave that has seen temperatures top 50 degrees Celsius (120 degrees Fahrenheit), protesters have railed against the poor quality of services, especially power outages that leave just a few hours of government-supplied electricity per day.

Thousands of people have turned out in Baghdad and cities in the Shiite south to vent their anger and pressure the authorities to make changes.

- Entrenched corruption -

Their demands were given a boost when Sistani called on August 7 for Abadi to take "drastic measures" against corruption, saying the "minor steps" he had announced were not enough.

The following Friday, Sistani said judicial reforms were needed, and Abadi responded by calling on the judiciary to carry out measures to ensure its independence and allow it to fight corruption.

Calls for change by Sistani, who is revered by millions, have shielded as well as influenced Abadi's efforts, as it is politically risky for rival Shiite politicians to publicly oppose measures called for by the top cleric.

But even with popular support and Sistani's backing, the entrenched nature of corruption and the fact that parties across the political spectrum benefit from it will make any efforts extremely difficult.

Earlier on Sunday, lawmakers said that a parliamentary investigation found former prime minister Maliki -- who is now a vice president -- to be among those responsible for IS jihadists overrunning Iraq's second city Mosul in June 2014.

Various former senior officials were also named in the report detailing the committee's findings, which has not been publicly released.

An MP on the committee said these include defence minister Saadun al-Dulaimi, army chief of staff Babaker Zebari, his deputy Aboud Qanbar, ground forces commander Ali Ghaidan, Nineveh operations command chief Mahdi al-Gharawi and the province's governor, Atheel al-Nujaifi.

- 'No one above the law' -

The report was presented Sunday to parliament speaker Salim al-Juburi, who said it will be sent to the prosecutor general for legal action.

"No one is above the law and questioning by the people, and the judiciary will punish those" responsible, Juburi said in a statement.

IS launched a devastating offensive on June 9 last year, overrunning Mosul the next day and then sweeping through large areas north and west of Baghdad.

While Baghdad's forces have regained ground, the jihadists still hold much of western Iraq, including the city of Ramadi, which they seized in May after government forces had held out against militants there for more than a year.

Abadi's office said Sunday that he had cleared the way for the military prosecution of senior commanders responsible for the disastrous loss of Ramadi.

Abadi approved "decisions of the investigative commission on the withdrawal of the Anbar operations command and units attached to it from the city of Ramadi", his office said in a statement.

Those include "referring a number of the leaders to the military judiciary for leaving their positions without orders and contrary to instructions (and) despite the issuance of a number of orders not to withdraw", it said.

Abadi previously said that forces in Ramadi "had to resist, and if they had resisted, we would not have lost Ramadi".

A senior British military officer in a US-led anti-jihadist coalition, Brigadier Christopher Ghika, said in June that the city "was lost because the Iraqi commander in Ramadi elected to withdraw".