Las Vegas-based Harrah's Entertainment, the focus of a $15.5 billion buyout proposal from two private equity groups, may be the target of another unsolicited offer, financial television network CNBC reported Tuesday.

Shares of Harrah's rose after the cable television network said Penn National Gaming and New York-based asset management firm D.E. Shaw & Co. were bidding for the company. Harrah's operates 40 casinos in 13 states, including seven Strip resorts.

The group would reportedly use financing from Lehman Bros. Holdings and Wachovia Corp. for a cash and stock offer for Harrah's, CNBC reported, citing unidentified sources. No value to the deal was given.

However, a source familiar with the discussions told the Review-Journal that D.E. Shaw, which is now part of a $470 million offer for Riviera Holdings Corp., was not part of the possible Harrah's deal.

D.E. Shaw and New York developer Bruce Eichner, who is building the $1.8 billion Cosmopolitan on the Strip, offered $21 a share on Nov. 13 for the outstanding shares of Riviera, which operates the Riviera on the Strip and slot machine casino in Colorado.

D.E. Shaw representatives did not wish to comment formally on the Harrah's report. A spokesman for Penn National, which had $1.41 billion in revenues a year ago and operates 16 casinos and horse racing tracks in 12 states and Canada, did not return phone calls. Penn National does not operate any casinos in Nevada.

Harrah's, the largest casino operator, received a takeover offer Oct. 2 from New York-based Apollo Management and Texas Pacific Group of Fort Worth, Texas. In the deal, the private equity groups offered to buy all outstanding shares of Harrah's for $81 a share. The offer was raised on Oct. 11 to $83.50 a share.

Harrah's announced initially in October that it received the offer and that nonmanagement members of the company's board of directors were evaluating the proposal.

Representatives of Apollo and Texas Pacific did not wish to comment on the reported offer from Penn and D.E. Shaw. Sources close to the private equity groups said, however, that it was surprising that Harrah's had not responded to the first buyout offer in almost two months.

Harrah's spokesman Alberto Lopez told Bloomberg News the company wouldn't comment on speculation.

"If we did have market-relevant news, we are very quick to release that info," Lopez said.

Harrah's shares closed at $78.46, up $1.91, or 2.5 percent, in trading on the New York Stock Exchange. Since the original buyout offer, Harrah's shares have climbed 18 percent.

Harrah's, which owns the Caesars casino brand, is an attractive takeover target because casinos offer steady cash returns, said Jake Balzer, a senior equity analyst at Guzman & Co. in Coral Gables, Fla.