US officials say the Coast Guard is pursuing a third oil tanker in international waters near Venezuela, as Washington steps up efforts to stop vessels it says are evading sanctions and operating as part of a so-called dark fleet.

The ship is identified in reports as Bella 1 and is described as sailing under a false flag. The pursuit follows two recent interdictions involving the tankers Centuries and Skipper, as the White House frames the wider campaign as linked to narcoterrorism and illicit financing.