Huge fireballs and thick plumes of smoke rose over Tehran after joint United States-Israeli air strikes hit fuel depots in the Iranian capital.

Iran’s oil distribution company said four of its employees were killed in the blitz, as a dark haze hung over the city on Sunday and the smell of burning oil lingered in the air.

Saturday’s strikes triggered large fires after hitting four oil storage facilities and an oil transfer and production centre in Tehran and neighbouring Alborz province, the Fars news agency reported. Iranian state media described the incident as an “attack from the US and the Zionist regime”.

The facilities targeted were the Aghdasieh oil warehouse in northeast Tehran, the Tehran refinery in the south, the Shahran oil depot in the west, and an oil depot in the city of Karaj. Witnesses said oil from the Shahran depot had leaked into nearby streets.

Israel said it had struck “a number of fuel storage facilities in Tehran” that were used “to operate military infrastructure”.

Shortly after the attacks, which appeared to mark a new phase in the war, Israeli Prime Minister Benjamin Netanyahu said his government would press on with the assault and strike Iran’s rulers “without mercy”.

“We have an organised plan with many surprises to destabilise the regime and enable change,” he said in a video statement. “We have many more targets.”

Joint US-Israeli attacks on Iran have continued for a ninth day, killing more than 1,300 people in Iran and about 300 in Lebanon, according to officials. About a dozen people have been killed in Israel.