Roche Holding AG (RHHBY) may have to soften its hardball tactics and lift the bid for the planned full acquisition of Genentech Inc. (DNA), analysts say.

Although Genentech's renewed rejection of Roche's full takeover attempt on Monday has hardened positions between the two, market watchers believe a tipping point has now been reached.

"It is clear that with Roche raising capital, there is no turning back and as such a sweetened offer should be expected", said Karl-Heinz Koch, pharma analyst at Helvea.

Roche has already raised around $16 billion through a six-part bond last week and is planning to raise more money by selling a four-part bond to finance its $42.1 billion planned acquisition.

Zuercher Kantonalbank also reckons that without raising its bid price of $86.50-a-share to acquire the remaining 44% in its U.S. biotech unit, Roche won't be able to gather enough shares before the tender period ends next month.

"Without doubt, Roche needs the innovation power of Genentech and may, because the financing is secured, offer a higher bid to Genentech," the bank said in an investor note.

Zuercher Kantonalbank expects Roche to present fresh takeover details about one week before the tender period ends on March 12.

A spokesman for Roche said the Swiss pharmaceuticals giant has registered Genetech's fresh rebuttal, adding that the "decision is up to Genentech's shareholders", declining to make further comments.

A special committee of Genentech's board Monday rejected Roche's bid and urged shareholders to follow its proposal, saying the current bid level is "inadequate and not in the best interest of shareholders".

Genentech is expected to convince shareholders of its views at its R&D meeting, which has been brought forward to next Monday, analysts said.

While Genentech has repeatedly said its shares were worth about $112 each, analysts say this level is too high and that the U.S. company will also have to revise its stance.

"We continue to believe that Genentech's ask price of $112 is too high", said Andrew Weiss, pharma analyst at Bank Vontobel, adding: "Eventually, Roche will need to improve its offer to $95 to $100."

The takeover battle for Genentech started last July, when Roche first approached its San Francisco, Calif.-based, unit about a full takeover. An initial takeover bid was launched at $89-a-share and was rejected by Genentech.

Roche later reduced its bid, turning the acquistion into hostile venture, hoping that such a hardball stance may prove equally successful as in the case of the takeover of Ventana Medical Systems Inc, a Tuscon, Ariz.-based, firm it acquired in 2007 despite resistance from the company's board.

-By Goran Mijuk, Dow Jones Newswires, +41 43 443 80 47; goran.mijuk@dowjones.com