Dell Inc has agreed to give Carl Icahn a closer look at its books less than a week after the activist investor joined a growing chorus of opposition to founder Michael Dell's plan to take the world's No. 3 personal computer maker private.

Dell shares rose 0.8 percent to $14.27, above the take-private offer price of $13.65, after Icahn said on Monday that his Icahn Enterprises LP reached a confidentiality agreement with the company and looks forward to "its review of Dell's confidential information."

Dell was not immediately available for comment.

Icahn demanded last week that Dell pay out $15.7 billion in special dividends instead of going private. He had argued that a proposed $24.4 billion buyout by Michael Dell, Silver Lake Partners and Microsoft Corp short-changed shareholders, undervalued the company and benefited mainly Michael Dell.

Cross Research analyst Shannon Cross said the move was just another step in Dell's commitment to examine alternative offers. But she said it "probably indicates Carl Icahn is serious about his proposal."

Icahn, whose arrival on the scene typically puts companies on guard, has said he wants the PC maker to pay $9 a share in dividends immediately from its own cash and from raising new debt.

He argued that, combined with a "stub" value of $13.81 per share that his firm calculated based on discounted cash flow, his proposal would deliver a total value of $22.81 per share.

That would be a 67 percent premium to the $13.65 buyout price put forward by Michael Dell.