US President Donald Trump has ordered a "total and complete" blockade of sanctioned oil tankers entering or leaving Venezuela, reports Saint Petersburg's PortNews.

In a post amplified by the White House, Trump said Venezuela was "completely surrounded by the largest Armada ever assembled in the history of South America." He added that all sanctioned oil tankers going into and out of Venezuela would be blocked.

The announcement followed the US seizure of the crude tanker M/T Skipper. The Department of Justice said the vessel was boarded and seized by the US Coast Guard on departing Venezuela, under a warrant signed November 26 by a magistrate judge.

The Treasury Department's Office of Foreign Assets Control had previously identified Skipper, formerly named Adisa, as part of an oil shipping network supporting Hizballah and Iran's IRGC-Qods Force, both designated foreign terrorist organisations by the US State Department.

US Attorney Jeanine Ferris Pirro said her office remained committed to supporting Trump's efforts, while FBI Director Kash Patel said the action highlighted successful efforts to impose costs on Venezuela and Iran.

Venezuela's government rejected the blockade in an official statement, calling it a "grotesque threat" and saying it violates international law and freedom of navigation.