To calm spirits on the peninsula, South Korea's top nuclear negotiator is to visit China and Japan this week.
They met with the main nuclear negotiator for North Korea, Kim Kye-gwan, and other senior leaders.
The council is led by Iran's chief nuclear negotiator, Ali Larijani.
Iran's top nuclear negotiator Saeed Jalili says his country is ready to return to the table.
"But he showed in his TV debates" with one of the nuclear negotiators "that he is not such an extremist."
Iran's top nuclear negotiator rejected calls for a prompt reply to an international proposal for resolving the dispute over its nuclear program.
His term as Iran's top nuclear negotiator, however, was limited to 678 days (from 6 October 2003 to 15 August 2005).
During a news conference in Iran, Ali Larijani, the country's security chief and top nuclear negotiator, condemned the West.
Still, Iran's chief nuclear negotiator stressed that differences remained.
The Secretary of the council doubles as the chief nuclear negotiator of Iran.