South Korea's imports of crude from Iran fell 7 per cent in June, against the daily average for the previous six months, less than half the rate Seoul has pledged it will cut oil shipments from the sanctions-hit country over the next six months.

To meet its pledge to Washington, South Korea needs to import less than 126,000 barrels per day (bpd) in the June-November period, but June's daily rate came in at 138,157 bpd, based on calculations on import data from the Korea Customs Service on Monday.

Countries that import Iranian oil must make continuous cuts to keep getting six-month waivers on US sanctions aimed at cutting Iran's flow of oil money and forcing it to negotiate over curbing its disputed nuclear programme.

South Korea promised to cut its Iranian oil imports by 15 per cent from the daily rate seen from December 2012 to May 2013, two sources told Reuters last month.

"Our monthly imports from Iran can vary, and we still have five more months to meet the pledge," said a source with direct knowledge of the matter but who was not authorised to speak to media.

The world's No. 5 crude buyer cut its Iranian crude imports to 565,444 tonnes in June, down nearly a quarter from a year ago, the preliminary data from Korea Customs Service showed.

On a daily basis, South Korea's imports were 16 per cent higher compared with May.

South Korea imported oil from Iran at a daily rate of 148,016 bpd for December to May, according to calculations based on data from state-run Korea National Oil Corp (KNOC).

That was in line with a earlier declared target of cutting the December-May volumes from Iran by 20 per cent from the same period a year earlier, helping it win its third waiver on sanctions from the United States.

Overall, South Korea imported a total 10.44 million tonnes of crude last month against 10.71 million tonnes imported a year ago, the customs data showed.

Final data for South Korea's crude oil imports last month will be published by KNOC later in the month. - Reuters