Korea, one of Iran's major Asian customers, shipped in 1.40 million tonnes of crude from Tehran in July, or 330,151 barrels per day (bpd), up from 1.10 million tonnes last year, customs data showed on Tuesday.
The worlds' fifth-biggest crude importer brought in 10.67 million tonnes of Iranian crude in the first seven months of this year, or 368,952 bpd, up 47.7 percent from 7.22 million tonnes over the same period last year, the data showed.
South Korea mainly imports Iranian condensate, an ultra-light oil used to produce more expensive fuels like naphtha. No breakdown of imports was available.
Iran, a member of the Organization of the Petroleum Exporting Countries (OPEC) is exempt from the oil cartel's deal to limit production to drain a global supply glut. The country is seeking to regain market share lost during the years it was under western sanctions over its nuclear programe.
In July, the Middle Eastern country exported 2.2 million bpd of oil to Asian and European markets, with its exports to Asia up by 100,000 bpd.
South Korea's intake of crude oil from top exporter Saudi Arabia fell 9.3 percent to 3.69 million tonnes, or 873,656 bpd, a year ago.
OPEC's July oil production rose further by 173,000 bpd to 32.87 million bpd, in the latest sign the oil producer club's joint efforts to cap output are weak.
Overall, South Korea's total July crude imports increased 3.2 percent to 12.44 million tonnes, or 2.94 million bpd, from a year ago, the data showed.
In the January-July of 2017, South Korea imported 84.68 million tonnes of crude, or 2.93 million bpd, up 2.0 percent from 83.04 million tonnes in the same period last year.