Brent crude futures jumped $6.11, or 6.76%, to $96.49 a barrel by ​2327 GMT, and US West Texas Intermediate was at $90.38 a barrel, ⁠up $6.53, or 7.79%.

The US military had seized an Iranian cargo ship that tried to run ​its blockade, US President Donald Trump said on Sunday, while Iran said it would ​not participate in a second round of peace talks despite Trump’s threat of renewed airstrikes.

The United States has maintained a blockade of Iranian ports, while Iran has lifted and then reimposed ​its own blockade of the Strait, which handled roughly one-fifth of the world’s ​oil supply before the war began almost two months ago.

“Oil markets continue to gyrate in response ‌to ⁠oscillating social media posts by the US and Iran, rather than the realities on the ground, which remain challenging for oil flows to resume in a rapid fashion,” Saul Kavonic, MST Marquee’s head of research, said.

Both contracts posted on Friday their ​largest daily declines since ​April 18 after ⁠Iran said passage for all commercial vessels through the Strait of Hormuz was open for the remaining ceasefire period, and Trump ​said Iran had agreed to never close the strait again.

“The ​announcement of ⁠the Strait opening proved premature,” Kavonic said.

“Ship owners will be twice shy about heading towards the Strait again without receiving much more confidence that any announced passage is ⁠real.”

More than ​20 ships passed the strait on Saturday carrying ​oil, liquefied petroleum gas, metals and fertilisers, Kpler data showed, the highest number of vessels crossing the ​waterway since March 1.