By David Morgan
WASHINGTON (Reuters) - China has failed to use its influence to stop North Korea's warlike rhetoric against the United States and U.S.-backed South Korea, despite an escalating crisis that could trigger armed conflict by accident, U.S. lawmakers said on Sunday.
Republican Senator John McCain, a member of the Armed Services Committee, criticized China's "failure to rein in what could be a catastrophic situation," saying Beijing could step up pressure on Pyongyang by using its influence over North Korea's economy.
"China does hold the key to this problem. China could cut off their economy if they want to. Chinese behaviour has been very disappointing," McCain said on CBS's "Face the Nation" program.
"More than once, wars have started by accident and this is a very serious situation," he added.
"South Korea would win. We would win if there was an all-out conflict. But the fact is that North Korea could set Seoul on fire. And that obviously would be a catastrophe of enormous proportions," McCain said.
Senator Chuck Schumer, a Democrat who has been a prominent critic of China's currency policy, said he agreed with McCain.
"The Chinese hold a lot of the cards here. They're by nature cautious. But they're carrying it to an extreme. It's about time they stepped up to the plate and put a little pressure on this North Korean regime," Schumer said on the same program.
North Korea has threatened war against the United States and the South in what analysts and U.S. politicians see as an attempt to wring concessions from the international community and shore up internal support for Pyongyang's 30-year-old leader, Kim Jong-un.
The senators' comments came as China, North Korea's sole financial and diplomatic backer, showed growing irritation with Pyongyang's vitriolic rhetoric toward the West.
Beijing has warned against "trouble making" on its doorstep in an apparent rebuke to North Korea, while Chinese leaders have spoken against provocative words and actions in the region.
On Sunday, the Foreign Ministry expressed "grave concern" and said China had asked North Korea to "ensure the safety of Chinese diplomats in North Korea, in accordance with the Vienna Convention and international laws and norms."
Meanwhile, the United States has postponed the long-scheduled test of its Minuteman III intercontinental missile to avoid what a defence official called "any misperception or miscalculation."
Former U.S. Ambassador to China Jon Huntsman told CNN on Sunday that it was unprecedented for Chinese President Xi Jinping to warn in a recent speech that no country "should be allowed to throw a region and even the whole world into chaos for selfish gain."
"It suggests to me, as I've watched the ratcheting up of frustration among Chinese leaders over the last many years, that they've probably hit the 212-degree boiling point as it relates to North Korea," Huntsman said.
The White House on Sunday had no immediate comment on recent Chinese statements.
But White House senior adviser Dan Pfeiffer told ABC's "This Week" program that North Korea is following a long-standing pattern of "provocative actions, bellicose rhetoric."
"The key here is for the North Koreans to stop their actions, start meeting their international obligations and put themselves in a position where they can achieve what is their stated goal, which is economic development," he said.
China also came under fire from Republican Senator Lindsey Graham, a leading voice on foreign policy issues who also sits on the Armed Services Committee.
"I blame the Chinese more than anybody else. They're afraid of reunification. They don't want a democratic Korea next to China, so they are propping up this crazy regime. And they could determine the fate of North Korea better than anybody on the planet," he said on NBC's "Meet the Press."
(Reporting by David Morgan; Additional reporting by Aruna Viswanatha; Editing by Eric Beech)