Britain should consider a Sweden-style selective military conscription system, a former head of MI6 has said.

Sir Alex Younger, who was chief of the Secret Intelligence Service from 2014 to 2020, argued that the UK needed a “wake-up call”.

In Sweden, people aged 18 have to complete an enlistment form, but only some of them are called up to do basic training with military service.

The selective form of conscription was reintroduced in 2017, with the move following Russia’s invasion of Crimea in 2014. Sweden joined the Nato military alliance in February.

Sir Alex told the BBC’s The Today Podcast: “Ultimately, in extremis, I think we’d be looking at something like the model I understand exists in places like Sweden, where the government theoretically has the power to compel people to give their service one way or another but doesn’t exercise it except in areas where it’s really needed.

“You’ll notice on that list is not everyone being called up and going to the drafting station, I think that’s extremely unlikely.”

Elsewhere in the interview, he said he was against “blanket conscription” but was interested in “ways in which the broader country would participate and contribute to security in a time of an emergency”.

Sir Alex appeared to agree that the UK needed to shift its thinking on defence matters in the manner of eastern European countries closer to Russia, such as Poland, Lithuania and Estonia.

He said: “I think in some ways those are people [bordering Russia] that have been mugged by reality, and I think I am a person that has been mugged by reality. And I’m a liberal through and through – I want to live in a world where we don’t have to think about this stuff.

“But I’m bound to say that we seem to have convinced ourselves somehow that the advantages we have and the values that are shot through our country are kind of natural and don’t need defending.

“And I think we’re in for a rude shock. And by contrast, if we do decide that we want to defend them, the need to do so probably goes down.”

He also said it was “rubbish” to think ideological and military rivalry was a thing of the past, adding: “I’m up for a wake-up call.”

The remarks come after Gen Sir Patrick Sanders, the head of the Army, said Britain should train a “citizen army” ready to fight a future war on land.

Gen Sir Patrick’s comments, made in January, triggered debate about whether conscription should return in some form. Downing Street rejected the idea at the time.