Spokesman Cho Tai-young said Tuesday that "significant progress" has been made on potential sanctions in response to Pyongyang's decision last month to conduct its third underground nuclear test, the Yonhap news agency reports.
"I expect a U.N. Security Council resolution this time to be tougher than Resolution 2087," he said, referring to sanctions that followed a December rocket launch.
Cho said South Korean and U.S. diplomats were negotiating the terms of a possible Chapter VII resolution, which would authorize the Security Council to use force to ensure compliance.
A senior diplomat confirmed, on condition of anonymity, that China was on board with draft resolutions under consideration by the Security Council.
Pyongyang said it would pull out of the 1953 armistice that suspended the Korean War unless the United States and South Korea hold off on military drills.
The North Korean government said its February nuclear test was part of a campaign against the United States. The rocket used to orbit a satellite in December had a range long enough to reach the U.S. West Coast.