The US Coast Guard is in active pursuit of another vessel in international waters near Venezuela, an official has told the BBC's US partner CBS News, as tensions in the region continue to escalate.

US authorities have already seized two oil tankers this month - one of them on Saturday.

Sunday's pursuit relates to a sanctioned dark fleet vessel that is part of Venezuela's illegal sanctions evasion, a US official said. It is flying a false flag and under a judicial seizure order.

Washington has accused Venezuela of using oil money to fund drug-related crime, while Venezuela has described the tanker seizures as theft and kidnapping.

US President Donald Trump last week ordered a blockade of sanctioned oil tankers entering and leaving the country.

Venezuela, home to the world's largest proven oil reserves, has accused the Trump administration of trying to steal its resources.

As of last week, more than 30 of the 80 ships in Venezuelan waters or approaching the country were under US sanctions, according to data compiled by TankerTrackers.com.

Saturday's seizure saw a Panamanian-flagged tanker boarded by a specialized tactical team in international waters.

The US claims this ship was carrying sanctioned PDVSA oil. These acts will not go unpunished, the Venezuelan government warned in response to Saturday's incident, expressing intentions to file a complaint with the UN Security Council.

Venezuela heavily relies on its oil exports to finance government spending, and recent weeks have seen an uptick in US military operations in the Caribbean amid allegations of drug trafficking linked to the Venezuelan government.

Critics have raised questions about the US's military actions, criticizing the lack of public evidence regarding the operations against alleged drug-smuggling vessels.