SEOUL (Reuters) - South Korea’s imports of Iranian crude oil jumped around 130 percent in May from the same month a year ago, extending gains after international sanctions were lifted in January on Iran’s nuclear program.

Seoul brought in 1.26 million tons of Iranian crude oil last month, or 297,625 barrels per day (bpd), compared with 541,510 tons imported a year ago, customs data showed.

In the first five months of the year, the world’s fifth-largest crude importer shipped in 5.08 million tons, or 244,917 bpd, of crude from the Middle Eastern country, versus 2.46 million tons in the same period in 2015, according to the data.

Iran, which is seeking to make up for lost trade following the lifting of sanctions imposed in 2011 and 2012 over its nuclear program, has emerged as OPEC’s fastest source of supply growth this year, the International Energy Agency said on Tuesday.

Overall, South Korea imported 12.43 million tons of crude last month, or 2.94 million bpd. The total was 4 percent lower than the 13 million tons imported in May of 2015, the customs data showed.

Final data for South Korea’s crude oil imports last month will be published by state-run Korea National Oil Corp (KNOC) later the month. The KNOC data is considered the industry standard for South Korea’s oil imports.