A former MI6 chief has said China represents a “generational threat” as he warned the UK’s relationship with Beijing could become more strained.

Sir Alex Younger who left the UK’s foreign intelligence service last year, said the pandemic had “closed the gap” between the two countries as he urged the UK to regain its technological and scientific advantage.

Speaking ahead of the publication of the Government’s Integrated Review of security, defence, development and foreign policy, Sir Alex said there would be an “ideological divergence” between the UK and China in the future.

He told BBC Radio 4’s Today programme: “There’s no doubt that China represents the generational threat, and the reason for that is that the idea that China will become more like us as it gets richer, or as its economy matured, is clearly for the birds.

“That’s not going to happen. On the contrary I expect China’s Communist Party to double down on its ideology in the future.

“There’s going to be an ideological divergence between us in the future, that’s going to generate rivalry and reduce trust.”

Asked if China will become the world’s biggest power, he added: “There’s no doubt that China feels advantage at the moment and the pandemic has closed the gap between us in some important ways.

“The language China understands is strength and we need to generate that strength through technological innovations and stewarding our alliances.”

Boris Johnson will set out the findings of the year-long review – billed as the most radical reassessment of Britain’s place in the world since the end of the Cold War – in the Commons on Tuesday.

The review says Russia under Vladimir Putin represents an “active threat”, but the language on China is more measured, saying Beijing poses a “systemic challenge”, according to a leaked copy obtained by the Guardian.

Sir Alex said Russia was “implacably hostile” to the UK and allied countries, and warned of weapons “they have quite successfully modernised that could do us enormous damage”.

“Russia, of course, or at least the Russian government, is implacably hostile to us and our allied countries, and I think that’s as a matter of their political legitimacy,” he told the Today programme.

“It’s in the Russian government’s interest for there to be a narrative of external threat to underpin the types of measures that they take to keep themselves in power.

“They have not been a constructive presence internationally, they have been highly disruptive and, of course, pretty uniquely, they have got weapons they have quite successfully modernised that could do us enormous damage.”

The review is said to warn there is a “realistic possibility” that a terrorist group will launch a successful chemical, biological, radiological or nuclear (CBRN) attack by 2030, according to the Times.

Sir Alex said he was not aware that a terrorist dirty bomb attack was an “imminent issue”, but added that the UK should “clearly” be prepared for the threat.