SINGAPORE: Oil prices jumped, the U.S. dollar lifted from lows and stock markets wobbled on Monday as rising tension in the Middle East kept shipping in and out of the Gulf to a bare minimum, though traders were holding out hope for a resolution.

The ceasefire in the Iran war, due to run until Tuesday, was in doubt after the U.S. seized an Iranian cargo ship and Tehran's top military command vowed to retaliate.

Iran has re-imposed its de facto closure of the Strait of Hormuz, though Kpler data showed that more than 20 vessels carrying oil products, metals, gas and fertiliser passed through it on Saturday, the busiest day for the chokepoint since March 1.

Brent crude futures jumped about 6% to $96 a barrel in early Asia trade. The dollar, which sold off sharply on Friday when the strait briefly opened, rose slightly.

S&P 500 futures fell around 0.7%, a modest move considering the index notched a record closing high on Friday. Asia-Pacific markets were mixed, with Australia's S&P/ASX 200 down 0.5% and Japan's benchmark Nikkei up 0.7%.

Bond markets, which rallied on Friday, retreated.

"The headlines look bad; it looks like there's disagreement ... which has led to a little bit of re-escalation," said Damien Boey, portfolio strategist at Wilson Asset Management in Sydney.