Oil prices gained more than 1% on May 28 on supply concerns as OPEC+ agreed to leave their output policy unchanged and as the U.S. barred Chevron from exporting Venezuelan crude.

Investors anticipated members of OPEC+ would agree to a production increase later this week.

Brent crude futures rose 91 cents, or 1.42%, to $65 a barrel by 1:48 p.m. EDT (1748 GMT). U.S. West Texas Intermediate crude gained $1.08, or 1.77%, to stand at $61.97/bbl.

OPEC+, the Organization of the Petroleum Exporting Countries and allies, agreed to establish a mechanism for setting baselines for its 2027 oil production. Some market watchers speak also of OPEC8+, or the eight members of the group that had been carrying on their own individual production cuts.

The meeting did not change output policy.

Most oil-producing countries at the meeting do not have the spare capacity to take barrels on and off the market, said Bob Yawger, director of energy futures at Mizuho. "They were hoping to slow the pace of production increases and stop the slide in price. But that's not the way it panned out," he added.

A separate meeting on May 31 of eight OPEC+ countries is expected to decide on an increase in oil output for July.

Goldman Sachs analysts see the group of eight keeping production steady after the July hike on new projects entering the market later this year, slowing economic growth and a build-up of oil stocks.

"However, we see the risks to our OPEC8+ supply path as skewed to the upside, especially if compliance doesn't improve or if hard demand data surprise further to the upside," they added.

Coming demand for the summer driving season is significant, and with non-OPEC+ crude output flat in the first half of the year, coupled with risks of Canadian wildfires hurting supply, the call on crude is stronger from OPEC+, said Janiv Shah, vice president of oil commodity markets analysis at Rystad Energy.

On May 28, Chevron terminated the oil production, service and procurement contracts it had to operate in Venezuela, but it plans to retain its direct staff in the country, sources said.

Both benchmarks ticked up in the previous session on concerns of tighter supply after the U.S. barred Chevron from exporting crude from Venezuela under a new authorization on its assets there.

Analysts also said prices could respond positively if there was progress on global trade talks or resolving U.S.-Iranian friction.

Iran's nuclear chief Mohammad Eslami said on May 28 it might allow the U.N. nuclear watchdog to send U.S. inspectors to visit nuclear sites if Tehran's talks with Washington succeed.

The American Petroleum Institute (API) trade group and the U.S. Energy Information Administration (EIA) are due to release U.S. oil inventory data on May 27 and May 28, respectively.

Analysts polled by Reuters estimated that crude inventories rose on average by about 100,000 bbl last week.

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