The US has seized a sanctioned oil tanker off the coast of Venezuela, President Donald Trump said on Wednesday, a move that sent oil prices higher and sharply escalated tensions between Washington and Caracas.

"We've just seized a tanker on the coast of Venezuela, large tanker, very large, largest one ever, actually, and other things are happening," said Trump, who has been pressuring Venezuelan President Nicolas Maduro to step down.

Asked what would happen with the oil, Trump said: "We keep it, I guess."

Trump has repeatedly raised the possibility of US military intervention in Venezuela.

This incident was the first known action against an oil tanker since he ordered a massive military build-up in the region.

The US has carried out strikes against suspected drug vessels, which raised concerns among lawmakers and legal experts.

US Attorney General Pam Bondi posted on X that the FBI, Homeland Security and Coast Guard, along with support from the US military, carried out a seizure warrant for a crude oil tanker used to transport sanctioned oil from Venezuela and Iran.

A 45-second video posted by Bondi showed two helicopters approaching a vessel and armed individuals in camouflage rappelling onto it. Trump administration officials did not name the vessel.

British maritime risk management group Vanguard said the tanker Skipper was believed to have been seized off Venezuela early on Wednesday.

The US has imposed sanctions on the tanker for what Washington said was involvement in Iranian oil trading when it was called the Adisa.

The Skipper left Venezuela's main oil port of Jose between December 4 and 5 after loading about 1.1 million barrels of Venezuela's Merey heavy crude, according to satellite info analyzed by TankerTrackers.com and internal shipping data from Venezuelan state oil company PDVSA.

Oil futures rose following news of the seizure. After trading in negative territory, Brent crude futures rose 27 cents, or 0.4 percent, to settle at US$62.21 a barrel, while US West Texas Intermediate crude futures gained 21 cents, also 0.4 percent, to close at US$58.46 per barrel.

Maduro on Wednesday spoke at a march commemorating a military battle, without addressing reports of the tanker's seizure.

Venezuela exported more than 900,000 barrels per day (bpd) of oil last month, the third-highest monthly average so far this year, as PDVSA imported more naphtha to dilute its extra heavy oil output.

Even as Washington increased pressure on Maduro, the US had not yet moved to interfere with oil flows.

"This is just yet another geopolitical/sanctions headwind hammering spot supply availability," Rory Johnston, an analyst with Commodity Context, said.

"Seizing this tanker further inflames those prompt supply concerns but also doesn't immediately change the situation fundamentally because these barrels were already going to be floating around for a while," Johnston said.

Chevron, which partners with PDVSA, said its operations in the country were normal and continuing without disruption.

The company, responsible for all Venezuelan crude exports to the US, last month increased crude exports to the US to some 150,000 bpd from 128,000 bpd in October. (Reuters)