South Korea Friday announced new sanctions on Iran because of its suspected nuclear weapons programme, restricting financial transactions with 99 Iranian firms and six individuals from the country.
A finance ministry official told reporters the new measures would not affect Iranian crude oil imports, which provide about 10 percent of South Korea's needs.
And Seoul would not impose an outright ban on Iranian petrochemical imports, the official said.
Britain, Canada and the United States slapped sanctions last month on Iran's financial, petrochemical and energy sectors following a UN nuclear agency report that strongly suggested Tehran is researching atomic weapons.
Robert Einhorn, the US State Department's special adviser for non-proliferation, visited Seoul last week to urge it to follow suit.
South Korea announced its initial sanctions in September last year. It said it would penalise a key Iranian bank and put all financial transactions with Tehran under strict government supervision.
Last year's measures included blacklisting 24 individuals and 102 Iranian entities as well as the strengthening of inspection of cargoes related to Iran.