Hopes that Cadbury will fend off the Kraft takeover bid have been dealt a blow with the news that a US shareholder is suing the confectioner for failing to properly consider its opening offer.

Steward International Enhanced Index Fund has filed a lawsuit in the New Jersey district courts against Cadbury chief executive Todd Stitzer, chairman Roger Carr and the board of directors, according to the Guardian.

“Cadbury shareholders stand to lose out massively if the board continues to refuse to negotiate a transaction with Kraft," Steward International claims in papers filed at court.

Cadbury turned down a £10.2bn bid for Cadbury last month after years of speculation over a possible approach. A letter from Carr to Kraft, subsequently published on the Cadbury website, described a takeover by the US food giant an “unappealing prospect”.

Earlier this week, the Takeover Panel imposed a deadline of 9 November for Kraft to formally launch a new offer.