SAUDI OSP: Saudi Aramco has raised its May price for its Arab Light grade for Asian customers by $0.10 a barrel versus April to a premium of $1.20 a barrel to the Oman/Dubai average, it said.

But the price hike confounded traders who were expecting cut of between 50 cents to 60 cents a barrel in a Reuters survey published earlier this week.

"This is a very unusual OSP," a trader with a North Asian firm said. "It's not in line with the past method of estimating prices."

It remains to be seen if other Middle East producers Iraq, Iran and Kuwait, who use the Saudi OSPs as a reference, will follow suit when they announce their prices next week.

The new OSP's widened the price gap between Arab Light and Arab Heavy by 30 cents to $3.25 a barrel, the widest since July 2016, Reuters data showed.

The spread usually widens during the summer season on stronger demand for light grades, a Singapore-based trader said.