Electricity shortages are a frequent complaint in Iraq, suffering from endemic corruption and dilapidated public infrastructure.

Most households rely on private generators, acquired to compensate for daily power cuts to public electricity.

On Monday, the electricity ministry said that "a record rise in temperatures" coupled with a surge in demand resulted in the shutdown of transmission lines, which then led to a total outage.

A senior ministry official, speaking on condition of anonymity, told AFP on Tuesday that "since midnight, all provinces have seen the return" of power supply.

The official cautioned that "it is happening gradually", with the central province of Karbala, where millions of Shiite Muslim pilgrims were expected for a major religious commemoration, being "the first to recover its electricity".

In the capital Baghdad, the grid was back to 95 percent of its normal capacity, said the official.

The outage came amid a heatwave that Iraqi meteorological services expect to last more than a week, with temperatures climbing as high as 50C in parts of the country.

While the vast majority of Iraqis rely on private generators, they often cannot power all household appliances, especially air conditioners.

Iraq is sometimes rocked by protests when outages worsen in the hot summer months.

To avoid outages during peak demand, Iraq would need to produce around 55,000 megawatts of electricity.

This month, for the first time, the country's power plants reached the 28,000-megawatt threshold.

The electricity ministry official said that "the system has returned to normal and is stable", producing 24,000 megawatts and expected to reach 27,000 once the final malfunctions related to Monday's outage are resolved.