The head of the International Energy Agency said on Monday that at least 40 energy assets across nine countries in the Middle East have been "severely or very severely" damaged since the Iran war began, raising fears of prolonged supply disruptions.

Speaking at the National Press Club in Australia’s capital, IEA Executive Director Fatih Birol said damage to oil and gas fields, refineries and pipelines across the Middle East would take some time to repair.

His comments come as market participants closely monitor threats from the U.S. and Iran over energy facilities as the sprawling regional conflict enters its fourth week.

The Iran war has severely disrupted energy trade flows through the strategically vital Strait of Hormuz, creating what the IEA says is the largest supply disruption in the history of the global oil market. The global supply of liquefied natural gas (LNG) has also been reduced by roughly 20% since the conflict began on Feb. 28.

Birol said the fallout from the Iran war is equivalent to the two major oil crises of the 1970s and the 2022 gas crisis "put together."

He added: "And, if I may, not only oil and gas. Some of the vital arteries of the global economy, such as petrochemicals, such as fertilizers, such as sulfur, such as helium. Their trade is all interrupted, which would have serious consequences for the global economy."

U.S. President Donald Trump on Saturday threatened to "obliterate" Iran’s power plants if Tehran did not fully reopen the Strait of Hormuz within 48 hours.

The narrow waterway is a key maritime corridor that connects the Persian Gulf and the Gulf of Oman. Roughly 20% of global oil and gas typically passes through it.

Iran’s Parliament spokesperson Mohammad Baqer Qalibaf responded, saying that critical infrastructure and energy facilities in the Gulf region could be "irreversibly destroyed" should Iranian power plants be attacked.

Given that shipping has virtually ground to a halt in the Strait of Hormuz since the conflict began, the IEA’s Birol said the reopening of the waterway was the "single most important" solution to the global energy crisis.

He singled out Asia as being at the forefront of the Iran war energy shock and said the IEA was prepared to follow-up its historic release of 400 million barrels of oil to the market on March 11.

"If it is necessary, of course, we will do it," Birol said.

— CNBC’s Anniek Bao contributed to this report.