Roche Holding AG has raised its offer to buy out the minority shareholders of U.S. biotech group Genentech Inc to $93 a share from $86.50 and extended its offer to shareholders by a week.

Based on conversations with Genentech shareholders, we believe that there is a strong sentiment to bring this process to a conclusion, Chairman Franz Humer said in the statement.

Roche is bidding to buy the 44 percent of Genentech it does not already own, with the raised offer valuing the stake at $45.7 billion, the company said.

As a result, we are increasing our price to $93 per share to maximize shareholder participation and will proceed quickly to complete all necessary financing. We now look forward to successfully completing the transaction, Humer said.

(Reporting by Sam Cage; Editing by Greg Mahlich)