Ryanair ’s chief executive has warned that some European airlines could go out of business if spiralling jet fuel prices remain high throughout the summer. Prices have surged dramatically since the war in Iran began on 28 February after the Strait of Hormuz , which, before the war, carried a fifth of the world's oil and gas, was blockaded by Tehran, leading to the worst fuel crisis for decades . The price of a barrel of Brent crude oil to be delivered in June fell 0.5 per cent to $110.71 early on Wednesday, but it remains considerably more expensive than before the war began, when it cost around $70 per barrel. That rise has meant the price of jet fuel has risen nearly 84 per cent since the start of the conflict. United Airlines and Lufthansa this week became the latest airlines forced to mull raising fares and scrapping flights as a consequence of that rise.…