UPDATE 1-Encore Acquisition looking at possible sale

(Adds company comment, stock activity)

HOUSTON, May 21 (Reuters) - Onshore oil and natural gas exploration company Encore Acquisition Co (EAC.N: Quote, Profile, Research) said on Wednesday it was exploring strategic alternatives, including a possible sale.

The Fort Worth company, which has acreage in the Bakken, Haynesville and Tuscaloosa Marine shale plays, said Lehman Brothers Inc has been hired as adviser.

"It is our belief that Encore's current share price is not reflective of our record operating results and our ability to efficiently fund these projects through our upstream master limited partnership, Encore Energy Partners," Encore Chief Executive Jon Brumley said in a statement.

The company said it will not provide any additional information until the board approves a transaction, if one occurs.

Encore shares rose about 4 percent in after-hours trading from its New York Stock Exchange close of $64.02.

(Reporting by Anna Driver in Houston, editing by Richard Chang)