WASHINGTON (AP) _ The State Department has issued a travel warning for all U.S. citizens in Nigeria as a result of rioting following the death of prominent opposition leader Moshood Abiola.

The travel warning, issued late Wednesday, said the U.S. Embassy in Lagos ``has received reports of rioting and looting in and around Lagos, specially on Lagos Island and the mainland.

``U.S. citizens are advised to avoid all uncecessary travel, especially by car, remain vigilant and avoid crowds. U.S. citizens should keep in touch with the U.S. Embassy for further updates,'' it said.