Venezuela's state-run oil company has announced it is cutting crude sales to ExxonMobil, the largest U.S. oil company, because of Exxon's efforts to seize Venezuelan assets.

Petroleos de Venezuela said in a statement Tuesday its move is retaliation for what it calls ExxonMobil's economic harassment.

ExxonMobil has not yet responded to Venezuela's decision.

British and Dutch courts last week granted ExxonMobil's demand to freeze as much as $12 billion in Venezuelan oil assets.

The company is challenging Venezuela's decision to nationalize a large oil project in which ExxonMobil had a large financial stake.

Venezuelan President Hugo Chavez has threatened to cut off oil sales to the U.S. if the court decision freezing the assets is upheld on appeal.

But a senior Venezuelan oil official Bernard Mommer said Tuesday Mr. Chavez is unlikely to carry out his threat, saying it would be costly for both countries.

The United States is Venezuela's biggest crude oil customer.

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