FRANKFURT (Reuters) - German utility RWE (>> RWE AG) is asking potential buyers of its oil and gas unit DEA to submit offers by late December in a deal that could fetch up to 5 billion euros (4.2 billion pounds), three people familiar with the matter told Reuters.

Wintershall, the oil and gas arm of German chemicals group BASF (>> BASF SE), has been the only group to publicly express interest in DEA so far.

Private equity investors such as KKR (>> KKR & Co. L.P.) and Blackstone (>> The Blackstone Group L.P.) are also likely to hand in bids, while British energy supplier Centrica (>> Centrica PLC) is expected to show interest as well, the sources said.

RWE, KKR, Blackstone and Centrica all declined to comment.

(Reporting by Arno Schuetze and Christoph Steitz; Additional reporting by Alexander Huebner in Frankfurt, Aizhu Chen in Beijing, Dinesh Nair in Dubai and Sarah Young in London; Editing by Jonathan Gould)