South Korea plans to announce a set of fresh sanctions on Iran as early as this week, diplomatic sources said Sunday, after the United States asked for such punishment for the Middle Eastern nation accused of illicit nuclear programs.

 "Related ministries are finalizing positions and this week will likely to be a turning point," a source said on condition of anonymity. "There will be an announcement in the near future as soon as technical and legal reviews are completed."

 Additional sanctions are likely to include banning Iranian petrochemical products in the form of asking South Korean companies to stop such imports, sources said.

 The U.S. and some other countries imposed sanctions on Iran's financial, petrochemical and energy sectors last month following a United Nations report that Tehran is researching nuclear weapons.

 Robert Einhorn, the U.S. State Department's special adviser for nonproliferation and arms control, visited South Korea last week and called for Seoul's cooperation. He also reportedly met with a senior finance ministry official to ask the country to join the sanctions, sources said.

 South Korea has been cautious about sanctions on Iran because such moves could have negative effects on its economy.

 Iran is one of South Korea's major business partners in the Middle East with their bilateral trade volume reaching about

US$14.5 billion during the first 10 months of this year. The amount is the highest ever, surpassing the previous annual record of $12.6 billion in 2008.

 South Korea has a relatively strong dependence on Iran's oil.

It brought in about 72.6 million barrels of crude oil from the country last year, about 8.3 percent of its total oil imports, according to the Korea National Oil Corp. (Yonhap News)