Iraqi oil production has slumped as the Iran war rages, with storage tanks reaching high and critical levels while the country is unable to export crude via the Strait of Hormuz, three Iraqi energy officials said on Wednesday.

Output from Iraq's main southern oilfields has further fallen by about 80% to around 800,000 barrels per day (bpd), the officials added.

Earlier this month, Iraqi oil production from its main southern oilfields had already fallen by about 70% to around 1.3 million barrels per day, as the country was unable to export crude via the Strait of Hormuz, industry sources said.

Production from the fields stood at around 4.3 million bpd before the war.

The officials said Iraq has decided to make further cuts in production from Tuesday, after asking BP to reduce output from the giant Rumaila oilfield by 100,000 bpd, cutting production to about 350,000 bpd from around 450,000 bpd previously.

Iraq also requested Italy's Eni cut production from the Zubair field by 70,000 bpd from a current output of 330,000 bpd. "Due to high and critical levels at its storage depots, please reduce production and pumping from North Rumaila to 350,000 barrels per day from current levels, starting at 0900 local time on March 24," said an official letter issued by state-run Basrah Oil Company and sent to BP, which was seen by Reuters.

A similar letter sent to Eni was also seen by Reuters. Iraq has also slashed output from different state-run fields, the sources added.

Iraqi energy officials warned that further production cuts could be announced in the coming days if the crisis in the Strait of Hormuz remains unresolved.

After successive cuts, production from Iraq's southern oilfields has fallen to around 800,000 bpd, as available storage space has become critically limited and exports remain halted, a senior oil official with knowledge of production operations said.

Two other Iraqi energy officials confirmed the figure.