British refineries have been asked to maximise jet fuel supply as part of government contingency planning, amid growing fears the Iran war will force planes to be grounded.

Energy minister Michael Shanks said the government is closely monitoring UK jet fuel stocks and working with airlines, airports, fuel suppliers and other governments, as carriers face rocketing fuel costs as a result of the conflict.

Normal flows of fossil fuels from the Gulf have effectively been at a standstill since the war broke out, after the de facto closure of the important shipping channel, the strait of Hormuz , through which a fifth of the world’s oil and gas flows.

“UK airlines typically buy fuel months in advance, and aviation fuel suppliers hold bunkered stocks.…