Plans specify tolls must not be compulsory, as US officials urge Iran to make public statement that strait is open and that shipping can safely pass

Europe is studying proposals that may allow the charging of navigational fees in the strait of Hormuz so long as the tolls are not compulsory and have the support of the UN agency that regulates maritime transport.

Britain’s deputy prime minister, David Lammy, said the imposition of compulsory tolls would be disastrous. But some of his cabinet colleagues said they recognised that systems of payments for specific navigational services were permissible in many natural waterways, including the strait of Malacca and the Channel.