Oil prices rose on June 1, with Brent topping $70, as optimism grew over the fuel demand outlook during the summer driving season of the United States, the world's top oil consumer.

Prices were also boosted after data from China showed that factory activity expanded at its fastest this year in May.

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Brent crude futures for August gained 83 cents, or 1.2%, to $70.15 a barrel by 0223 GMT. U.S. West Texas Intermediate crude for July was at $67.61 a barrel, up $1.29, or nearly 2% from Friday's close, with no settlement price for Monday due to a U.S. public holiday.

"While there are concerns over tighter COVID-19 related restrictions across parts of Asia, the market appears to be more focused on the positive demand story from the U.S. and parts of Europe," analysts from ING Economics said in a note on June 1.

"In the U.S., the summer driving season officially got underway following the Memorial Day weekend, and we have entered this period with gasoline inventories already trending lower, and not too far from a 5-year low for this time of the year."

Tracking firm GasBuddy said Sunday's U.S. gasoline demand jumped 9.6% above the average of the previous four Sundays, the highest Sunday demand since the summer of 2019.

The price gains were capped, though, as more output is expected to hit the market.

OPEC+ is likely to agree to continue to slowly ease supply curbs at a meeting on June 1, OPEC sources said, as producers balance an expected recovery in demand against a possible increase in Iranian output.

OPEC+ decided in April to return 2.1 million barrels per day (bbl/d) of supply to the market from May to July, as it anticipated global demand would rise despite surging coronavirus cases in India, the world's third-largest oil consumer.

"We believe that the market will be able to absorb this additional supply, and so would expect the group to confirm that they will increase output as planned over the next 2 months," ING Economics analysts added.