A ship was set ablaze off the coast of the United Arab Emirates and another was damaged off Qatar, underscoring the ever-present danger also facing vessels due to Iran's stranglehold on the Strait of Hormuz.
Saudi Arabia had begun pumping large volumes of oil west to avoid the strait and ship it from the Red Sea, but the security of that route was called into question after Iran's drone hit the country's SAMREF refinery in the Red Sea port city of Yanbu.
Qatar, a key source of natural gas for world markets, said firefighters put out a blaze at a major LNG facility after it was hit by Iranian missiles.
Production had already been halted after earlier attacks but it said the latest wave of missiles caused "sizable fires and extensive further damage."
A drone attack on Kuwait's Mina Al-Ahmadi refinery sparked a fire but caused no injuries, the state-run KUNA news agency reported. The refinery is one of the biggest in the Middle East, with a petroleum production capacity of 730,000 barrels per day.
Shortly after, a drone attack set ablaze the nearby Mina Abdullah refinery, officials said.
Authorities in Abu Dhabi said they were forced to shut down operations at its Habshan gas facility and Bab field, calling Iranian overnight attacks on the sites a "dangerous escalation."
Qatar, Saudi Arabia and the UAE all denounced the Iranian attacks, with Saudi Arabia's top diplomat saying assaults on the kingdom meant "what little trust there was before has completely been shattered."
The wave of Iranian attacks came after Israel hit South Pars, the Iranian part of the world's largest gas field located offshore in the Persian Gulf and owned jointly with Qatar.
US President Donald Trump said an angry Israel "violently lashed out" and attacked Iran's major gas field before threatening to "massively blow up the entirety of" South Pars.
Trump said the United States did not have advance knowledge of Israel's attack, adding that Qatar had not been involved.
He went on to say Israel would not attack South Pars again "unless Iran unwisely decides to attack a very innocent, in this case, Qatar," adding in that case the US "will massively blow up the entirety of the South Pars Gas Field at an amount of strength and power that Iran has never seen or witnessed before."
Earlier, the Wall Street Journal said Trump had approved of Israel's plan to attack Iran's natural gas field.
South Pars is the Iranian sector of the world's largest natural gas deposit, which Iran shares with Qatar, a close US ally and host of the United States' biggest military base in the Gulf.
Since the start of the conflict, Tehran has targeted not just Israel, but US diplomatic and military facilities across the Gulf and warned its neighbours not to host attacks on Iran.
With de-escalation nowhere in sight, Trump is considering sending thousands more US troops to the Middle East, according to a US official and three people familiar with the planning.
Those troops could be used restore the safe passage of oil tankers through the Strait of Hormuz, a chokepoint for a fifth of the world's oil trade.
The foreign ministers of 12 Muslim-majority countries meeting in Riyadh denounced Iran's strikes on Gulf neighbours and called for an immediate halt.
Iran's targeting of residential areas and civilian infrastructure, such as oil facilities, airports and desalination plants, could not be justified under any circumstances, the ministers said in a statement.
"This pressure from Iran will backfire politically and morally and certainly we reserve the right to take military actions, if deemed necessary," Saudi Foreign Minister Prince Faisal bin Farhan told a press conference after the diplomats met in Riyadh.
The UAE shut down its Habshan gas facility after it intercepted missiles fired in what its foreign ministry called a "terrorist attack" by Iran.
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".
More than 3000 people have been killed in Iran since the US-Israeli attacks began on February 28, the US-based Iran human rights group HRANA estimates.
Authorities in Lebanon say 900 have been killed there and 800,000 forced to flee their homes.
Iranian attacks have killed people in Iraq and across the Gulf states, and at least 13 US military service members have been killed in the war.
with AP and DPA
