Seoul: A senior US official on Monday urged South Korea and other allies to expand sanctions on imports from Iran for its suspected nuclear weapons programme, calling the Islamic country "a pariah state".
Robert Einhorn, the US State Department`s special adviser for non-proliferation and arms control, said the allies should show a "clear and unified message".
"The situation in Iran has become more and more worrisome over recent months," he said, accusing Iran of showing "little interest in seriously negotiating over their nuclear programmes".
"Iran is violating its international obligations... it is becoming a pariah state," he told reporters during a trip to Seoul.
Einhorn said allies should ban petrochemical imports from Iran, except for crude oil.
"The timeline for Iran`s nuclear programme is beginning to get shorter. So it`s important that we take these strong steps on an urgent basis," he said.
Britain, Canada and the US slapped sanctions last month on Iran`s financial, petrochemical and energy sectors following a UN agency report that strongly suggests Tehran is researching nuclear weapons.
The European Union followed suit by expanding a sanctions blacklist against Iranian firms and individuals, although Iran dismissed the UN report as baseless.
The US Congress is also considering legislation targeting Iran`s central bank -- the nexus for receiving payment for oil exports -- despite White House concerns that Iran could benefit if oil prices shoot up.
Einhorn ruled out a need for South Korea to ban imports of crude oil from Iran, saying Washington was aware of "energy security needs of countries" like South Korea.
"We would like to see a reduction in Iran`s revenues from the sale of crude oil... but at the present time the oil market is very tight," he said.
South Korea in September 2010 announced a package of sanctions against Iran in line with US-backed United Nations action. But there was no ban on oil imports which provide 10 percent of South Korea`s needs.
China, the European Union, India, Japan, South Korea and Turkey are the main customers for Iran`s oil exports – a major source of income of the Middle East state.