By David French and Carl O'Donnell
(Reuters) - Anadarko Petroleum Corp, the U.S. oil and gas exploration and production company that agreed this month to sell itself to Chevron Corp for $33 billion (£25.5 billion), decided on Sunday to begin negotiations to sell itself to Occidental Petroleum Corp instead, according to people familiar with the matter.
Anadarko's board of directors has decided that Occidental's $38 billion cash-and-stock bid could lead to a deal that would be superior to the one it has with Chevron, the sources said.
Anadarko will now kick off negotiations with Occidental to see if it can finalise a deal, the sources added.
There is no certainty that Occidental, which was vying for Anadarko before Chevron clinched its deal, will be able to secure its own deal, the sources said. If it does, Chevron will be given an opportunity under its contract with Anadarko to match Occidental's deal.
The sources asked not to be identified because the matter is confidential.
Anadarko, Occidental and Chevron did not immediately respond to requests for comment.
(Reporting by David French and Carl O'Donnell in New York; editing by Richard Pullin)