South Korea imported 5.896 million barrels of Iranian crude oil in January, a 16.1% drop from a year earlier, preliminary data from the state-run Korea National Oil Corp. showed Friday.

Monthly crude imports from the Middle Eastern country are likely to continue recording on-year declines over the next few months as South Korea continues efforts to gain exemption from having to fully comply with U.S. sanctions targeting Tehran's oil exports.

South Korea's imports of Iranian crude were about 190,200 barrels a day last month, up from 184,600 barrels a day in December, according to the preliminary data.

In January, South Korea relied on Iran for 7.2% of its crude needs, compared with 8.9% a year earlier, the data showed.

South Korea was granted another 180-day exemption from U.S. sanctions in December, the country's second grace period. This grace period expires early June and South Korea will have to start negotiating again with the U.S.--possibly around May--on the extent of potential cuts to crude imports from Iran.