The company, with headquarters in London and Houston, announced the move Monday.

"We believe that this is a very opportune time to sell our U.S. business," said Chief Executive Officer Graeme Thomson. "In particular, I am very excited about Kurdistan and Madagascar where independent studies have indicated a combined unrisked net economic value at potentially over $2 billion if both prospects are successful at the best estimate level."

Sterling signed the controversial production-sharing contract with Iraq's Kurdistan Regional Government last November. The KRG is looking to capitalize on an unexplored but prospective wealth of oil reserves despite Baghdad's desire to have central control over oil development in the country.

Sterling said in a statement the Kurdistan and Madagascar reserves combined are estimated at between 500 million and 1.9 billion barrels of oil.