Britain and other European countries must boost their defence spending to bear a greater share of the costs of Nato, Bernie Sanders, the Democratic presidential candidate has said.

In comments that echoed those of Donald Trump on the costs of the Western alliance system, Mr Sanders said the United States was responsible for 75 per cent of Nato’s military costs - which he said amounted to it supporting the economies of richer European countries.

His remarks came in Thursday’s Democratic debate in New York - broadcast by CNN - with Hillary Clinton, his Democratic opponent and the former American secretary of state, in answer to a question from interviewer Dana Bash.