European natural gas futures extended earlier gains and in after-hours trading on Wednesday after a fragile ceasefire between the US and Iran effectively collapsed following a new wave of military strikes, escalating tensions in the Persian Gulf and raising concerns about energy supply disruptions.
The front-month Dutch TTF contract rose by 5.387% to 49.085 euros ($55.98) per megawatt hour, while the UK NBP front-month contract gained 4.966% to 116.250 British pence ($1.55) per therm.
The gains extended Wednesday's rally, which pushed European gas prices to their highest level in nearly a month after renewed military activity on July 7-8, Trading Economics said.
US forces carried out preemptive and retaliatory airstrikes on more than 80 targets across southern Iran, prompting Iran's Islamic Revolutionary Guard Corps to launch retaliatory ballistic missile and drone attacks against US military bases in Kuwait and Bahrain, news outlets reported.
The renewed hostilities have disrupted commercial shipping lanes in the Persian Gulf and prompted several regional states to activate air defense systems.
Adding to market uncertainty, Iranian media outlets affiliated with the Islamic Revolutionary Guard Corps called for Tehran to abandon last month's agreement with Washington. US President Donald Trump said earlier Wednesday that the agreement could be over, while indicating negotiations might still continue.
Fars News Agency, which is linked to the Guards, said: "Iran too should announce the official end of the initial understanding, the related negotiations, and future talks." Tasnim News Agency said Iranian officials should respond by "burning the understanding" themselves, according to the New York Times.
The renewed geopolitical tensions have intensified concerns over Europe's ability to replenish gas inventories ahead of the winter heating season.
European gas storage facilities were 50.63% full, compared with 60.65% at the same point last year, Gas Infrastructure Europe said. Inventories also remained well below the five-year average of 65.7% for this time of year, according to the Swiss Federal Office of Energy.
Supply concerns were compounded after gas flows from Norway, Europe's largest pipeline supplier, declined slightly as seasonal maintenance was extended, according to Trading Economics.
Persistent heatwaves across Europe have also complicated storage refilling by boosting cooling demand. In a social media post, Severe Weather Europe said on Wednesday that temperatures in Valencia, Spain, approached 45 degrees Celsius (113 degrees Fahrenheit), while about 150 weather stations across the continent recorded temperatures above 40 degrees Celsius.