FILE PHOTO: The Occidental Petroleum Corp headquarters is pictured in Los Angeles, California September 16, 2013. REUTERS/Mario Anzuoni

(Reuters) - Oil and gas producer Anadarko Petroleum Corp on Wednesday confirmed Occidental Petroleum Corp’s $57 billion offer for the company that topped Chevron Corp’s $50 billion bid and said it would carefully review the offer.

Occidental’s surprise $76-per-share proposal comes after the company had repeatedly said in recent weeks that it had been trying to woo Anadarko in an effort to become the largest producer of oil in west Texas’s Permian basin, where production has boomed in recent years.