China's behavior amid the surge in tensions on the Korean peninsula shows that it is "not a responsible world power," US Senator John McCain charged Sunday.

McCain's remarks came as the United States and South Korea began naval operations in a potent show of force, just days after Pyongyang bombarded a South Korean island, killing four people.

"The key to this, obviously, is China. And unfortunately China is not behaving as a responsible world power," McCain, the ranking Republican member of the Senate Armed Services Committee, said on CNN's "State of the Union."

"It cannot be in China's long-term interest to see a renewed conflict on the Korean Peninsula," he added.

China "could bring the North Korean economy to its knees if they wanted to. And I cannot believe that the Chinese should, in a mature fashion, not find it in their interest to restrain North Korea. So far, they are not," he stressed.

China has not joined other world powers in criticising the North's island bombing.

US military chief Admiral Mike Mullen also Sunday called on China to take a stronger stand against Pyongyang, which he said poses a serious threat.

"It's hard to know why China doesn't push harder," he said on CNN, adding they try to keep Kim under control.

"I'm not sure he is controllable," Mullen said.

The risk, "if we get it wrong, all of us, including China," is that North Korea could, eventually, "be able to threaten ballistically -- a ballistic missile capability which will threaten the United States and others."

Earlier Sunday, China called for "emergency consultations" in Beijing early next month among chief envoys to the stalled six-nation talks on the North's nuclear disarmament.

Its top envoy on North Korea, Wu Dawei, speaking in Beijing, stressed the proposal did not constitute a formal resumption of the negotiations. But he said he hoped they would lead to such a resumption soon.