South Korea has imposed fresh sanctions involving limiting of financial transactions on Iran to force it to scrap its suspected nuclear weapons programme.

South Korea added 99 Iranian groups and six individuals to a list of people and organizations banned from foreign-exchange transactions without approval from the Bank of Korea, the finance ministry said in a statement today. It had blacklisted the Seoul branch of Bank Mellat and 101 other Iranian companies under international sanctions last year.

The ministry said it would alert domestic companies importing petrochemicals to be cautious of the risks they face because of US sanctions. “We will ask domestic companies to pay attention to international sanctions when purchasing petrochemical products from Iran,” Eun Sung Soo, a director-general at the finance ministry, told reporters.

South Korea, the world's fifth largest crude oil importer, follows Britain, Canada and the U.S, who put forward sanctions last month on Iran's financial, petrochemical and energy sectors. The U.S. has been urging allies to unite in its attempts to put an end to the nuclear ambitions of Iran following the report from the International Atomic Energy Agency, which indicated that Teheran was working on a nuclear bomb.

Iran is South Korea’s fourth-largest supplier of crude oil and accounted for 8.3 percent of the 870 million barrels imported in 2010, according to the state run Korea National Oil Corp.

South Korea imported about $333 million worth of petrochemicals from Iran in 2010, accounting for around 2.5 percent of imports of the products, according to the Korea Petrochemical Industry Association and the Korea International Trade Association.