Guidant, the US healthcare company, last night filed a lawsuit against Johnson & Johnson in an attempt to force it to complete a $25.4bn (€21.6bn) takeover, set to be one of the largest merger and acquisition deals of the year.

In the lawsuit, filed in the US District Court for the Southern District of New York, Guidant said Johnson & Johnson was obliged to close the merger after the deal was given final regulatory approval last week.