South Korean President Park Geun Hye on Wednesday urged China to agree to stronger sanctions against North Korea following Pyongyang's recent nuclear test.
"China has a very important role to play," Park said in a speech in Seoul.
China - Pyongyang's biggest ally - has said it opposes North Korea's nuclear weapons programme, but Park said Beijing's position should be underscored through action.
Pyongyang says it detonated a hydrogen bomb on January 6. Other nations have since cast doubt on the claim, but the test nevertheless triggered worldwide outrage.
The UN Security Council pledged last week to take "significant measures" against North Korea and said it would begin working on a resolution in response to the test.