UPDATE 1-Elliott raises offer for Riverbed to $3.36 bln

Feb 25 (Reuters) - Hedge fund Elliott Management increased its offer for network gear maker Riverbed Technology Inc to $3.36 billion from $3.08 billion and said it was aware of other potential buyers that Riverbed had so far ignored.

The new offer of $21 per share represents a 5.8 percent premium to the stock's closing price of $19.85 on Monday.

Riverbed's stock rose as much as 7 percent to $21.19 after the announcement on Tuesday.

Riverbed rejected Elliott's earlier offer of $19 per share, on Jan. 15.

The hedge fund said on Tuesday it would not increase its offer "in the absence of private diligence."

Elliott said that Riverbed had ignored overtures from other potential bidders even though they appeared to be willing to offer materially more for the company than it was.

Elliott, run by Paul Singer, disclosed a 10.5 percent stake in the company on Tuesday.