Getty ImagesRas Laffan Industrial City, pictured on 3 MarchA major gas field in Qatar has been hit by missile attacks, causing "extensive damage", the country's state-run energy firm has said.
The Iranian strikes follow reports that Israel hit a petrochemical complex in Iran.
The attack on Qatar's Ras Laffan gas field has sent gas prices soaring.
What is Ras Laffan and what does it do?
Ras Laffan Industrial City is Qatar's main site for producing liquefied natural gas (LNG) which is used globally for cooking, heating homes and generating electricity.
It produces about a fifth's of the world's supply of LNG.
As well as processing LNG, the industrial hub's other facilities include a gas-to-liquids plant, LNG storage and an oil refinery.
It is located 80km (50 miles) north-east of the capital, Doha, and close to Qatar's North Field, a huge gas field covering an area of more than 6,000 sq km (2,315 sq miles).
It is run by the state energy company QatarEnergy. Several international energy firms also have operations there, including US giants ExxonMobil and Chevron and the UK's Shell.
Production has been shut down there since early March, shortly after war broke out.
What is happening to gas prices?
QatarEnergy confirmed overnight that Ras Laffan had been subjected to two missile attacks, one that resulted in "extensive damage" to Shell's Pearl gas-to-liquids facility, and one that caused "sizeable fires and extensive further damage" to several of its LNG facilities.
Gas prices, which had already been rising since the start of the conflict, surged.
When trading began on Thursday morning, UK gas prices briefly surged over 30%, and are currently up about 22% at 170p per therm.
European gas prices are also up 20% on Thursday.

Matthieu Favas, commodities editor at The Economist, said the rise in prices was "huge".
Analysts fear that the latest attacks mark an escalation in the conflict and that disruption to supply could continue for longer than initially thought.
What will happen now?
Energy research and consultancy firm Wood Mackenzie said the Ras Laffan attacks "fundamentally reshape [the] global LNG outlook" and the timeline for recovery was "likely significantly extended".
"Market expectations had been for a short disruption, with a controlled restart restoring supply to pre-conflict levels by mid-2026. That outlook now appears increasingly unlikely," said Kristy Kramer, head of LNG strategy and market development.
Nick Butler, former head of strategy at BP and former adviser to Gordon Brown, agreed, that the market was now expecting things to get worse.
"This will almost certainly cut off a level of supply of LNG to the world market. The price of gas in the world market will therefore inevitably rise, because that gas can't be substituted very quickly at all, and maybe not for a very long time."
However, Favas said prices were still a long way off the peaks seen in the aftermath of Russia's invasion of Ukraine.
How does this affect people in the UK?
Even if you get your energy from another source such as solar or nuclear power, gas makes up a large part of the UK's "energy mix".
The energy regulator, Ofgem, uses gas as "the marginal source of power", which sets prices for wholesale electricity in the UK.
So when gas prices go up, it has a big impact on electricity prices.
"In the short term, someone is going to have to pay more and we need to be planning for that," Butler said.
"I think now we've come to a stage where the government will have to come in with a plan for energy security and a plan for protecting people who are going to pay these higher prices in two or three months' time as the market works through."
QatarOil & Gas industryIran warNatural gas
