Icahn was quoted in The Wall Street Journal as saying: "I'm very cynical about many of the boards and CEOs in this country, but even I am amazed at the lengths that Jerry Yang and the board went to entrench themselves in this situation."
Court documents published in The New York Times state that Icahn is accusing Yang of never seriously considering Microsoft's proposed acquisition of Yahoo, and of imposing measures which would make an acquisition impossible.
Microsoft abandoned its pursuit of Yahoo in May after the two sides failed to agree a deal on the price of the acquisition.
Yahoo has since maintained that it is open to further negotiations with Microsoft should the software giant be interested.
After the talks collapsed, Icahn began a proxy fight to collect enough shares and support from investors to replace Yahoo's board with a group that would be more willing to cut a deal with Microsoft.
Yahoo almost immediately countered Icahn's threat, saying in an open letter that the board believes it has more than enough support from investors to thwart any sort of takeover bid by Icahn and his allies.
Icahn, however, remains confident that he can take control of the board and bring Microsoft back to the table.
"In my opinion, you might have to get rid of Jerry and part of the board to bring back Microsoft," he told The New York Times.
"Microsoft will have to tie up US$45 billion for an entire year, and they might want to do it with someone they trust."
Yahoo's next shareholder meeting is scheduled for 1 August.
Icahn vows to yank Yang from Yahoo
By Shaun Nichols on Jun 5, 2008 8:08AM