"President Hu said the Korean nuclear issue is now at a crucial point," spokesman Liu Jianchao told reporters on the sidelines of an Asia-Pacific Economic Cooperation (APEC) summit in Hanoi.
"In this kind of situation, the most important step is to return to the six-party talks and see if all parties concerned can once again reaffirm the concessions they made... so that six-party talks can make progress and lead to concrete results."
The North detonated a small atom bomb on October 9, sparking global outrage and UN sanctions, but two weeks ago agreed to return to six-party talks involving both Koreas, the United States, China, Russia and Japan.
The talks have been in limbo for a year after Pyongyang walked out in protest at US financial sanctions against its overseas bank accounts.
The Chinese spokesman added that Roh had said "he hoped that the parties concerned can show flexibility and make concessions to create favourable conditions for the resumption of the six-party talks.
The South Korean president "hopes to strengthen communication and consultation with China to jointly contribute to peace and stability in Northeast Asia," Liu said.
US President George W. Bush said Friday he would push Roh in weekend talks to fully implement UN sanctions imposed on North Korea after its nuclear test.
"I'll, of course, talk to the South Korean president about implementing the United Nations Security Council resolution," Bush told reporters.
Bush is also due to meet Hu, Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe.
"I'm meeting with all our partners in the six-party talks," said Bush.
Liu said communication channels remained open with Pyongyang.
"China, North Korea and the United States keep in touch in various ways," he told AFP. "They aren't just in touch once or twice. The way they keep in touch varies and so does the venue. Sometimes, it's Beijing, sometimes it's New York. It's not a problem to get in touch."

Copyright AFP (Agence France-Presse), 2006