The US has seized a sixth tanker in the Caribbean Sea in its ongoing efforts to control exports of Venezuelan oil, officials say.

The vessel, Veronica, was boarded in a predawn operation 'without incident' as it was defying President Donald Trump's 'quarantine of sanctioned vessels', said the US military.

'The only oil leaving Venezuela will be oil that is coordinated properly and lawfully,' the Southern Command said.

Since the US military strikes on Venezuela and seizure of its president Nicolás Maduro this month, Trump has said he plans to tap into the country's huge oil reserves.

'The Veronica is the latest tanker operating in defiance of President Trump's established quarantine of sanctioned vessels in the Caribbean,' US Southern Command said in a post on social media. It also posted a video showing Marines and sailors boarding the tanker.

Veronica, a crude oil tanker sailing under a Guyanese flag, had departed empty from Venezuelan waters in early January, according to monitoring service TankerTrackers.com. The International Maritime Organization's database shows the vessel was previously registered in Russia under different names.

Homeland Security Secretary Kristi Noem posted on social media that Thursday's tanker seizure was carried out with 'close coordination with our colleagues' in the military as well as the state and justice departments. 'Our heroic Coast Guard men and women once again ensured a flawlessly executed operation, in accordance with international law,' Noem added.

This suggests Washington's crackdown on the so-called dark fleet, comprising more than 1,000 vessels that transport sanctioned oil, will continue as the US works with Venezuela's interim government to control the country's oil sales.

The latest seizure comes a day after an American official said the US had completed its first sale of Venezuelan oil, valued at $500m.

Trump last week asked oil executives at the White House to invest $100bn in Venezuela's energy infrastructure. They said significant changes would be needed to make the country an attractive investment.

The blockade has sharply curtailed Venezuelan oil exports, with only ships associated with Chevron and bound for the US operating as usual, according to Matt Smith, head of US analysis at Kpler. Loadings have fallen roughly in half this month to about 400,000 barrels per day, he said.

The Veronica incident highlights the direction of US maritime policy amid escalating tensions and the evolving situation surrounding Venezuelan oil.

}