ATP Completes First Step of Monetization

Business Wire, June 9, 2008

HOUSTON -- ATP Oil & Gas Corporation (NASDAQ:ATPG) today announced the completion of the sale of a limited term overriding royalty interest for $82 million at a value of $14.25 per Mcfe. T. Paul Bulmahn, ATP Chairman and CEO, stated, "For ATP this is a first step in demonstrating the substantial value created in our inventory of properties. While the volumes associated with this limited term override are less than 1% of our company-wide proved reserves at year-end 2007, the sale represents a significant beginning to ATP's company monetization goals."

Total limited term override volumes sold are capped at 5.76 Bcfe (27% natural gas and 73% crude oil). The 15% limited term overriding royalty represents 3.63% of the proved and probable reserves at the Gomez Hub (Mississippi Canyon 711/755/754/800) as of December 31, 2007. Payout is projected to be accomplished during 2009.

About ATP Oil & Gas Corporation

ATP Oil & Gas is an international offshore oil and gas development and production company with operations in the Gulf of Mexico and the North Sea. The company trades publicly as ATPG on the NASDAQ Global Select Market. For more information about ATP Oil & Gas Corporation, visit www.atpog.com.

Forward-looking Statements

Certain statements included in this news release are "forward-looking statements" under the Private Securities Litigation Reform Act of 1995. ATP cautions that assumptions, expectations, projections, intentions, or beliefs about future events may, and often do, vary from actual results and the differences can be material. Some of the key factors which could cause actual results to vary from those ATP expects include changes in natural gas and oil prices, the timing of planned capital expenditures, availability of acquisitions, uncertainties in estimating proved reserves and forecasting production results, operational factors affecting the commencement or maintenance of producing wells, the condition of the capital markets generally, as well as our ability to access them, and uncertainties regarding environmental regulations or litigation and other legal or regulatory developments affecting our business. The SEC has generally permitted oil and gas companies, in filings made with the SEC, to disclose only proved reserves that a company has demonstrated by actual production or conclusive formation tests to be economically and legally producible under existing economic and operating conditions. We and our independent third party reservoir engineers use the terms "probable" and "possible" and we use the term "recoverable hydrocarbons" to describe volumes of reserves potentially recoverable through additional drilling or recovery techniques that the SEC's guidelines may prohibit us from including in filings with the SEC. These estimates are by their nature more speculative than estimates of proved reserves. All estimates of probable and possible reserves in this news release have been prepared by our independent third party engineers and all estimates of recoverable hydrocarbons have been prepared by management. More information about the risks and uncertainties relating to ATP's forward-looking statements are found in our SEC filings.