Donald Trump is “right” to criticise Nato’s European members for failing to “pull their weight” in defence spending, a senior British diplomat has said.

Sir Adam Thomson, the Permanent Representative to Nato, said the Republican presumptive presidential nominee was justified in rounding on European states for relying on the US for their defence at a time of “severe challenges” including the spread of Islamic State and Russian destabilisation of Ukraine and eastern Europe.

“Nato is the cornerstone of UK national defence, and Nato is at the heart of European defence.

“So, Donald Trump right about one thing, which is that Europeans do need to start pulling their weight when it comes to investing in defence,” said Sir Adam.

“Europe should not expect to lean so heavily on the United States to bankroll Europe’s security and defence. The UK feels ale to stand up and say this because we are one of regrettably very few Nato countries that has met, and will continue to meet, all Nato’s spending targets.”