Reuters - South Korea's intake of Iranian crude oil soared to a record high in March and its first-quarter crude imports from Iran nearly doubled on year, reflecting Tehran's efforts to raise output after the lifting of sanctions early last year.

The increase in volumes since international sanctions against Tehran were lifted in January 2016 has made Iran the second-largest oil supplier to South Korea after Saudi Arabia, in the first quarter of 2017, according to preliminary customs data on Saturday. Iran was fifth-largest in the first quarter of 2016, behind Saudi Arabia, Iraq, Kuwait and Qatar, according to data from Korea National Oil Corp (KNOC).

The official KNOC data ranked Iran as second-largest for the first two months of the year. The KNOC figures for March and the quarter are due out in one week.

In March, the customs data showed South Korea imported 2.26 million tonnes of Iranian crude, or 534,368 barrels per day (bpd), up 118.8 percent from 1.03 million tonnes a year ago, reaching a record. That was up 38.3 percent from 1.63 million tonnes in February.

The world's fifth-largest crude importer and one of Tehran's biggest customers shipped in 5.68 million tonnes of Iranian crude in the first three months of 2017, or 463,234 bpd, up 92.4 percent from the 2.96 million tonnes imported during the same period a year ago.

Meanwhile, oil shipments from Saudi Arabia to South Korea, rose 10.9 percent to 3.52 million tonnes, or 831,413 bpd, in March on year. That was down 2.6 percent from 3.61 million tonnes a month ago as the world's top oil exporter complies with the OPEC deal to cut supplies.

The Organization of the Petroleum Exporting Countries (OPEC) and some non-OPEC members reached an agreement to curb output last year by almost 1.8 million bpd in the first half of 2017. Iran was exempted from the deal.

Korea's crude oil imports from Saudi Arabia fell 10 percent to 10.44 million tonnes in the first quarter of this year, or 850,614 bpd, from 11.61 million tonnes in the previous quarter, but that was 5.7 percent higher on year.

Overall, Asia's fourth-largest economy brought in 12.68 million tonnes of crude oil in March this year, or nearly 3 million bpd, up 10.1 percent from 11.52 million tonnes a year ago, according to the data.

For the first quarter of 2017, South Korea imported 36.94 million tonnes of crude, or 3.01 million bpd, up 4.6 percent from 35.32 million tonnes a year earlier.

Final data for the country's March crude oil imports will be released by state-run Korea National Oil Corp (KNOC) later this month. (Reporting by Jane Chung; Editing by Tom Hogue and Bill Trott)