US independent Occidental Petroleum has set the stage for a takeover battle for Anadarko Petroleum after tabling a $57 billion offer designed to usurp a lower bid made earlier this month by supermajor Chevron.

Houston-based Oxy argued its cash-plus-shares proposal, which also includes debt, is superior to the $50 billion deal agreed between Chevron and Anadarko on 14 April, pointing to vastly higher synergies it expects through the combination of the two companies.