The refinery, which can process 730,000 barrels of oil per day, was already damaged on Thursday in another Iranian attack. It is one of three oil refineries in Kuwait, the tiny, oil-rich nation on the Persian Gulf. Iran stepped up its attacks on energy sites in Gulf Arab states after Israel on Wednesday bombed Iran’s massive South Pars offshore natural gas field in the Persian Gulf. With some 80pc of power generated in Iran coming from natural gas, the attack posed a direct threat to the country’s electricity supplies. In Israel, sirens sounded early on Friday, warning of attacks on Jerusalem and in the north of the country, sending people again scrambling to shelters.