A deal could be announced by Diamondback with closely held Endeavor as soon as Monday, the report said, adding that Diamondback fended off competition from other parties including ConocoPhillips in striking a deal.

Endeavor and Diamondback did not immediately respond to a Reuters request for comment.

Reuters in December reported that Endeavor Energy Partners was exploring a sale that could value the largest privately held oil and gas producer in the Permian basin at between $25 billion and $30 billion.

The sale would come almost 45 years after Texas oilman Autry Stephens started the company that would become Endeavor.

Endeavor's operations span 350,000 net acres (1,416 square kilometers) in the Midland portion of the Permian shale basin that straddles West Texas and eastern New Mexico.

(Reporting by Utkarsh Shetti in Bengaluru; Editing by Josie Kao and Mark Porter)