In a statement, the Japanese firm said that the media reports regarding Roche’s intention to own 100% of Chugai shares is not based on any announcement made by Chugai or Roche.
The company was in no way in the process of reviewing any plan to become a wholly-owned subsidiary of Roche, nor discussing with Roche about such a transaction.
The speculative talks come 12 years after Roche acquired a majority stake in Chugai for about $1.4bn.
The Swiss drug firm already owns about 60% of the Japanese firm and is said to be looking to acquire the remainder for about $10bn (Dh36.7bn).
In the past three months, Roche agreed to three significant acquisitions worth a combined $2.5bn. They include the $1.7bn purchase of Seragon Pharmaceuticals of the US and the acquisitions of Santaris of Denmark and Genia of the US.