NEW YORK,(Reuters) - Dubai World and casino operator MGM Mirage are set to boost their joint tender offer for MGM shares, going after a bigger stake and setting the price at the high end of a previously stated offer, the Associated Press reported.

The revised offer, to be announced on Wednesday, would be for 15 million shares at $80 each, the AP reported, quoting an executive.

Dubai World would buy 6.5 million of the shares offered, increasing its stake in the company to 9.4 percent, while MGM Mirage would buy 8.5 million, the report said.

MGM executives were not immediately available for comment.

MGM Mirage and state-owned investment company Dubai World said last week that they will make a cash tender offer for 10 million MGM shares at between $75 and $80 each.

Dubai World started building up its stake in MGM in August 2007 as part of a deal that included the purchase of MGM shares and the acquisition of a 50 percent stake in MGM's massive CityCenter project in Las Vegas.