Roche -- seeking to shore up its position amid declining sales of its antiviral drug Tamiflu and a strong Swiss franc -- launched a hostile offer last week to acquire, directly from stockholders, the 44 percent of Genentech it does not already own for $86.50 a share.

That tender replaced Roche's $89-a-share bid for Genentech from last July, which was turned down by independent directors of the San Francisco-based Genentech for being inadequate.

Roche was not available for comment on Monday.

"The special committee intends to take a formal position regarding the Roche offer within ten business days, and will explain in detail its reasons for that position by filing a statement ... with the Securities and Exchange Commission," Genentech said in a statement.

Pharmaceutical companies like Roche have proven relatively resilient during the economic downturn as healthcare is typically one of the last areas where customers cut spending. But last week, Roche warned of slower growth in 2009 after quarterly results missed expectations.

Roche's chief executive, in an interview with Reuters on February 6, said he thought the offer fully valued Genentech's pipeline of experimental medicines.

Shares of Genentech were up a marginal 0.4 percent in after hours trade at $83.00 versus a regular $82.70 close.

Roche now needs to acquire 90 percent of Genentech shares in order to complete a merger.

If it falls short of that goal, the company has said it will review options, including doing nothing, purchasing shares in the open market or via privately negotiated transactions, making a new offer or seeking to negotiate a merger or other business combination with Genentech.

(Reporting by Edwin Chan; Editing by Bernard Orr)