Cash Dubai's premium to Dubai swaps, was at $1.79 a barrel, the highest since at least 2014, the data showed. DME Oman's premium to Dubai swaps also touched $1.90 a barrel on Monday, the highest since October.

The United States is expected to announce on Monday that buyers of Iranian oil need to end imports soon or face sanctions, a source familiar with the situation told Reuters, triggering a 3 percent jump in crude prices to their highest for 2019 so far.

Buyers will have no choice but to pay more for alternative supplies if the United States decides to stop waivers for Iranian oil buyers, traders said.

MIDEAST: Taiwanese oil refiner CPC has bought three cargoes of Upper Zakum crude for June loading in its monthly tender, trade sources said.

The refiner bought the cargoes at premiums of 10 cents to 15 cents a barrel to the grade's official selling price (OSP), they said, similar premiums compared with earlier deals for the grade.

Thailand's PTT also bought medium sour grades on behalf of refiner IRPC although details were not immediately available.

RUSSIA: Spot premiums for Sokol crude continued to climb, rising to a five-month high after Exxon Mobil sold a cargo at $4.60 a barrel above Dubai quotes in the latest deal for the grade, trade sources said.

Exxon sold one of two cargoes it offered in a tender late on Thursday, they said. The buyer was not immediately known.

ASIA-PACIFIC CRUDE: Petronas has sold a June-loading Labuan crude cargo at a premium of more than $5.50 a barrel to dated Brent to an unknown buyer, a trader said.