Chugai Pharmaceutical Co has denied a report published by Bloomberg that Roche was going to pay $10 billion to take full control of the Japanese company.

The Tokyo-based firm said that the report “is not based on any announcement made by Chugai or Roche”. It is “in no way in the process of reviewing any plan to become a wholly-owned subsidiary of Roche, nor discussing with [the Swiss major] about such a transaction”.

Bloomberg had cited unnamed sources supposedly familiar with the matter that Roche was in talks to buy the 38% of Chugai it does not own. It took a controlling 50.1% stake back in October 2002 for about $1.4 billion and has increased its stake since then.

Roche has shied away from major acquisitions of late and chief executive Severin Schwan said last month he is more interested in bolt-ons. Recently it has bought US firm’s Seragon Pharmaceuticals (up to $1.7 billion) and Genia Technologies (up to $350 million), plus Denmark’s Santaris (up to $450 million).

Chugai is focused on oncology, as well as renal and bone diseases. Sales reached $4.4 billion last year.