NEW YORK, Feb 8 - The government of Ghana has blocked the estimated $4 billion sale of a stake in its Jubilee oil field, foiling months of talks between potential buyer Exxon Mobil Corp and the stake's owner, Kosmos Energy LLC, the Wall Street Journal reported on Monday.

A Ghanaian official said state-run Ghana National Petroleum Corp would be the only entity allowed to buy Kosmos' stake in the field, the Journal said.

The Ghanaian government is "unable to support an Exxon Mobil acquisition of Kosmos's Ghana assets," the Journal said, citing a letter that Ghanaian Energy Minister Joe Oteng-Adjei reportedly sent to Exxon.

Exxon spokesman Patrick McGinn said the company does not "comment on the details of commercial discussions or opportunities," adding only that it "routinely evaluates potential development opportunities around the world."

Officials at the Ghanaian government could not immediately be reached for comment.

Kosmos is backed by U.S. private equity funds Blackstone Group LP (BX.N) and Warburg Pincus