The government has intervened in the planned £4bn takeover of Cobham, a UK aerospace and defence supplier, by a US private equity firm on the grounds of national security.

Andrea Leadsom, the business secretary, has instructed the Competition and Markets Authority to investigate the takeover of Cobham, a world leader in systems for planes to refuel in mid-air, by Boston-based Advent International.

Leadsom said: “Following careful consideration of the proposed takeover of Cobham, I have issued an intervention notice on the grounds of national security. The government’s goals are to support private sector innovation whilst safeguarding the public interest.”

Shareholders on Monday approved the sale for cash of Cobham, established 85 years ago by the aviation pioneer Sir Alan Cobham, against the wishes of the founding family, which owns 1.5% of the company.

The takeover was opposed by some shareholders, opposition MPs and Nadine Cobham, the widow of Sir Alan’s son, who called on Leadsom to step in to protect the business. Advent has said it will review Cobham’s businesses, raising concerns it was planning to break up the company.

Cobham employs about 10,000 people, including 2,000 in the UK, and operates in more than 100 countries. The company supplies radar and other electronic products for the defence and aviation industries, including mid-air refuelling technology used by RAF planes to extend their range.

The government stepped in amid disquiet over sales of UK companies to foreign bidders or buyers intending to break up valuable businesses. Last year, when Melrose Industries succeeded with a hostile takeover last year of GKN, another engineering company that supplies the defence industry, the deal was opposed by unions and some MPs. The government eventually extracted concessions from the buyer. Melrose had to agree not to sell on the aerospace part of the GKN business for five years and provide commitments about levels of research and development spending at GKN.

Private equity firms have been snapping up UK companies such as satellite provider Inmarsat and theme park operator Merlin Entertainments, attracted by low prices caused by the weak pound and Britain’s reluctance to block takeovers. The buyout firms traditionally hold on to a purchase for three to five years before selling it on, leading to accusations of asset stripping.

Blackstone, the world’s biggest private equity firm, said Brexit had made the UK the best place to do deals among developed economies. It’s not just about what’s coming; it’s about the price I have to pay for it,” Blackstone’s president, Jonathan Gray, told investors, according to Bloomberg.

Cobham has only recently steadied itself after five profit warnings between 2015 and 2017 and critics have accused Advent, one of the biggest US buyout firms, of snapping up the company cheaply as it recovers. Its chief executive, David Lockwood, said he regretted the sale when the company was showing signs of revival.

Shares in Cobham were down less than 1% in afternoon trading after the minister’s announcement at 159.75p – slightly below the agreed purchase price of 165p. Analysts said with only about 8% of Cobham’s business in the UK the government was likely to allow the deal to go ahead.

John Colley, professor of practice at Warwick Business School, said: “In the case of national security interests any attempted acquisition is very likely to be referred to the CMA. In this case the buyer is foreign and ultimately will sell the business on to someone else. The CMA, after appropriate consultation, may still allow the sale.”

The government can intervene in takeovers in the public interest on the grounds of national security, concentration of media ownership and financial stability. Of the nine national security interventions, seven have been cleared after the bidder made concessions and one was cleared without concessions. The decision on Inmarsat’s takeover by two private equity firms is pending.

Leadsom, who was appointed business secretary by Boris Johnson in July, has told the CMA to report back by 29 October. Advent and Cobham said they would work with the government and were committed to the deal.