Ecuador has revoked a contract with the U.S. oil company Occidental Petroleum Corporation, accused of illegally selling its stock.

Ecuador's energy minister Ivan Rodriguez told reporters the government declared the contract void and accepted a lawsuit brought by Ecuador's state-owned oil company, Petroecuador. Occidental said in a statement that it is evaluating its legal options to defend its interests. The company also says it has complied with all obligations under its contract with the government.

Occidental Petroleum has been in a dispute with Ecuador over an allegedly illegal stock transaction. Authorities in Quito say Occidental transferred oil stocks to a Canadian oil company without notifying the Ecuadorean government.

The dispute sparked protests by residents calling for the company to be expelled.

Occidental produces about 100,000 barrels of crude oil daily in Ecuador.

Some information for this report was provided by AFP, AP and Reuters.