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

All other terms and conditions of the offer -- now pitched at $45.7 billion for the 44 percent of the U.S. biotech group Roche doesn't already own -- remain unchanged, Roche said in a statement on Friday.

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.

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.

Shares in Genentech, the world's biggest biotech company by market value, jumped 10 percent to $89.75 on news of the revised offer, which analysts said would clearly tempt some investors.

This is going to be significantly more difficult for minority shareholders to turn down, Geoffrey Porges, an analysts for Sanford Bernstein said.

I don't think this a slam dunk at $93, but it's got a much higher probability of success than $86.50.

Analysts had generally agreed that Roche's offer of $86.50 had little chance of success, especially since it represented a decline from the $89 initially suggested in July.

The Swiss drugmaker said that it had, so far, received acceptances for just 500,000 shares under the tender process.

The offer at $86.50 had been due to expire on March 13 but Roche said it was now extending this until March 20.

Nick Turner of Mirabaud Securities in London said $93 was a pretty decent premium over what Genentech might be trading at if there was no Roche offer on the table.

As to whether they (Genentech management) would recommend at this level, that's another matter -- it's always been in my mind that management would hold out for $95 and above, he added.

(Additional reporting by Ben Hirschler in London and Bill Berkrot in New York; Editing by Greg Mahlich)