Qatar's state oil giant QatarEnergy reported "extensive damage" after the Ras Laffan Industrial City, an energy-industry hub, was hit by Iranian missiles on Wednesday.
Saudi Arabia said it had intercepted and destroyed four ballistic missiles launched toward Riyadh on Wednesday and an attempted drone attack on a gas facility in the east of the country.
The escalation threatens to worsen an unprecedented disruption to global energy supplies that has raised the political stakes for US President Donald Trump. Diesel prices in the United States have already risen above $US5 ($A7.10) a gallon for the first time since the 2022 inflation surge that eroded support for his predecessor Joe Biden.
The conflict that has already halted shipping from the world's most important energy-producing region and could now bring lasting damage to its infrastructure. Benchmark Brent crude prices rose around five per cent to above $US108 ($A153). Stock markets veered lower.
Pars is the Iranian sector of the world's largest natural gas deposit, which Iran shares with Qatar across the Gulf.
The attack was widely reported in Israeli media to have been carried out by Israel with US consent, though neither country acknowledged immediate responsibility.
Qatar, a close US ally which hosts the largest US airbase in the region, blamed the attack on Israel, without mentioning any US role, and called it "dangerous and irresponsible" that put global energy security at risk. The UAE also denounced the attack.
Iran listed an array of prominent regional oil and gas facilities it called "direct and legitimate targets" - Saudi Arabia's Samref Refinery and Jubail Petrochemical Complex, the UAE's Al Hosn Gas Field, and Qatar's Mesaieed Petrochemical Complex, Mesaieed Holding Company and Ras Laffan.
It said they should be evacuated at once before it struck them in the coming hours.
The US and Israel had previously held back from targeting Iran's energy production facilities in the Gulf, averting Iranian retaliation against the oil and gas industries of its neighbours.
Iran has already shut the Strait of Hormuz, which handles 20 per cent of global oil and liquefied natural gas supply, but consuming nations have hoped the disruption would prove short-lived as long as production infrastructure was spared.
Israel killed Iran's intelligence minister Esmail Khatib on Wednesday, a day after killing powerful security chief Ali Larijani, and Israeli Defence Minister Israel Katz said "no one in Iran has immunity and everyone is in the crosshairs".
He and Prime Minister Benjamin Netanyahu had authorised the Israeli military "to target any senior Iranian official for whom an intelligence and operational opportunity arises, without the need for additional approval."
US-based Iran human rights group HRANA on Monday said an estimated 3000-plus people had been killed in Iran since the US-Israeli attacks began on February 28. Authorities in Lebanon say 900 people have been killed there and 800,000 forced to flee their homes.
Iranian attacks have killed people in Iraq and across the Gulf states. Fourteen have been killed in Israel.
Meanwhile, Trump does not want any further strikes on Iranian energy infrastructure after Israel's attack on the South Pars gas field on Wednesday, the Wall Street Journal reported on Wednesday, citing US officials.
Trump, who knew about the Israeli strike on South Pars in advance, supported it as a message to Tehran over its blocking of the Strait of Hormuz, and could again be open to targeting more Iranian energy facilities depending on Tehran's future actions in the waterway, the Journal said.
Reuters could not immediately verify the report.
