The sale of a Welsh microchip manufacturer to a Chinese-backed company poses a greater threat to Britain’s interests than Huawei’s involvement in the 5G network, according to the UK’s former cyber security chief.

Prime Minister Boris Johnson has asked National Security Adviser Sir Stephen Lovegrove to examine the purchase of Newport Wafer Fab by Chinese-owned Nexperia for a reported £63 million, with MPs calling on ministers to urgently intervene.

Ciaran Martin, who was chief executive of the National Cyber Security Centre (NCSC) until August, said the future of microchip supply was a “first order strategic issue” for the country.

Mr Martin was in charge of NCSC when it changed its security assessment of equipment made by Huawei last year, ultimately excluding the firm from the UK’s 5G rollout on security grounds.

He told the Telegraph: “Huawei in the periphery of 5G only really mattered because the Trump administration became obsessed with it for reasons they never convincingly set out.

“By contrast the future of semiconductor supply is a first order strategic issue. It goes to the heart of how we should be dealing with China.”

It comes after the influential Commons Foreign Affairs Committee (FAC) said the UK’s “sovereignty should not be for sale” as they called for tougher action to prevent strategically important companies being sold overseas.

The cross-party report earlier this month called for the takeover of Newport Wafer Fab to be formally called in for review, with the Government imposing “appropriate mitigation measures”.

Committee chairman Tom Tugendhat said at the time: “Our fiercest competitors, notably China, have a track record of using foreign investments to gain access to important technologies and information.

“We’ve witnessed too many of our country’s brilliant tech firms disappear abroad with potentially significant economic and foreign policy implications.”