A leading shareholder in UK defence company Cobham has said it plans to vote against its £4 billion acquisition by a US private equity firm.

Sanderson Asset Management, the 11th largest shareholder of the company, has put its weight behind criticism from the founding family of Cobham over the move.

Lady Nadine Cobham, whose late husband Michael ran the business, wrote to the company's largest investors last week arguing that the offer significantly undervalued the firm after a recovery over the past two and a half years.

Lady Cobham, who owns a 1.5% stake in the business, has written to Defence Secretary Ben Wallace and Business Secretary Andrea Leadsom calling on them to intervene in the buyout by US-based Advent International.

In a letter back to Lady Cobham, Sanderson said it has told the company board about its plans to vote against the deal, becoming the first institutional investor to openly oppose the move.

In the letter, Christian Paaskesen, senior portfolio manager for Sanderson, said: "We broadly agree with your assessment of the offer and are inclined to vote against it.

"We have privately communicated our position to the board along with our desire to see the current management team continue their good work in the event a better offer does not materialise."

Investors have been hoping a rival bidder will emerge to drive up the value of the business, which employs around 10,000 people, including 1,700 in the UK.

Advent International has received support for its offer to buy the company from Cobham's management as well as shareholder Artemis Investment Management.

Shareholders in Cobham have until Monday September 16 to decide on the offer, which needs support from three-quarters of investors.

Shares in the company fell 2% to 156.4p in trading on Tuesday.