The price of 20 litres of 95-octane petrol shot up nearly 16,000 Lebanese pounds ($10.6 at the official rate) to reach 61,000 pounds ($40.6), according to NNA.
Import prices rose 1.1% last month after gaining a 0.8% in April.
The report also showed export prices jumped 2.2% in May after rising 1.1% in April. Prices for agricultural exports rose 6.1%, the largest gain since in November 2010.
The closure of Colonial Pipeline's 5,500-mile (8,900-km) system was the most disruptive cyberattack on record, preventing millions of barrels of gasoline, diesel and jet fuel from flowing to the East Coast from the Gulf Coast.
The national gas price on Monday hit $3.045 a gallon, the highest since October 2014, according to data from the American Automobile Association.
Rice prices in the peri-urban areas of Yangon and the second largest city, Mandalay, were meanwhile up four percent since the last week of February, the WFP said.
European refining margins are still lower than a year ago, but rising prices and narrowing price spreads between gasoil futures delivery months indicates a tightening market, analysts said.
