Johnson & Johnson has bowed out of a potential merger with Actelion, opening up the field for an unconfirmed contender widely believed to be French drugmaker Sanofi.

The US healthcare giant confirmed that it has withdrawn from discussions over a potential takeover, which would have bolstered its lung disease offering with Actelion's pulmonary arterial hypertension portfolio.

The firm did not give a detailed reason for the move, saying only that it had not been able to reach an agreement that would create adequate value for its shareholders.

But Reuters has cited people close to the situation saying that the Swiss biotech told J&J that it could attract an offer significantly above the approximate 250 Swiss francs per share (reportedly around $27 billion) it had laid on the table, and that there were issues over the deal structure.

Actelion confirmed that it is "engaged in discussions with another party regarding a possible strategic transaction," but stressed that "there can be no certainty at this point that any transaction will result".

The Wall Street Journal has reported that this party is Sanofi, also citing people close to the situation.