The new Business Secretary Andrea Leadsom is being urged to protect the UK's interests

Andrea Leadsom has been urged to intervene in the £4billion takeover of defence group Cobham to protect the UK’s national interests.

In a letter to the new Business Secretary, Liberal Democrat MP Chuka Umunna said that the company provided vital capabilities to the armed forces.

Umunna, who is his party’s business spokesman, described Cobham as one of the jewels in the crown of UK industry but claimed it was being ‘sold on the cheap’.

His intervention is the latest sign of growing opposition to a bid by American buyout firm Advent International to take the British company private.

Critics, including the Cobham family, say the deal could cause jobs and expertise to be lost from the UK’s defence industry. Umunna claimed the takeover also risked loading Cobham with ‘excessive’ debt.

But in his letter, seen by the Mail, he added that the weak pound had left the company – and others based in the UK – looking cheap and attractive to foreign buyers. He said: ‘The alarm bells are ringing and yet the Government has chosen to ignore them and gives the appearance of having abandoned this important industrial asset.

‘The issue with this deal is not that Cobham faces being bought by a foreign company but that this particular purchase has a material impact on the UK’s national security and manufacturing base. It is vital you and your department act now.’

Cobham was founded in 1934 by aviation pioneer Sir Alan Cobham and employs about 10,000 people, including 1,700 in the UK.

It is a major contractor for the Ministry of Defence and the US Department of Defense, specialising in systems that let aircraft refuel while in the air. Its technology proved vital to Britain during the Falklands War and is used today by Airbus planes and F-35 fighter jets.

It was left reeling by profit warnings in 2016 and 2017, but under boss David Lockwood it embarked on a turnaround strategy and reported a £71million profit last year compared to a loss of £847.9million in 2016.

Last month however the board recommended the takeover bid by Advent. It requires the backing of at least 75 per cent of shareholders in a vote.

But top shareholder Silchester International Investors, with an 11.8 per cent stake, is opposed. arguing that a higher price can be secured.

The deal has so far been supported publicly by Artemis Investment Management, which owns 5.4 per cent of shares. A spokesman for the Government previously said it was ‘closely monitoring’ the takeover process.