Kim Kye Gwan left Beijing after refusing to take part in six-party talks to push forward a February agreement calling for North Korea to begin winding down its nuclear programs in return for energy aid and political considerations.
Kim waved to reporters at the airport but did not say anything.
China issued a statement saying the talks would take a recess but did not give a restart date.
"The parties agreed to recess and will resume the talks at the earliest opportunity to continue to discuss and formulate an action plan for the next phase," it said.
The breakdown raises doubts over meeting a deadline in the Feb. 13 denuclearization agreement that calls for U.N. inspectors to verify the closure of North Korea's main nuclear reactor at Yongbyon by April 14.
But the top U.S. nuclear envoy said he was still optimistic that disarmament deadlines can be met despite the breakdown.
"It is our strong view that we are still on schedule," Assistant Secretary of State Christopher Hill said, referring to the April deadline that calls for U.N. inspectors to verify the closure of North Korea's main nuclear reactor at Yongbyon.
State Department spokesman Sean McCormack told reporters in Washington that envoys were expected to meet again within the next week or two.
In Tokyo, Japanese Prime Minister Shinzo Abe criticized North Korea for not being constructive. "It's clear there is nothing for North Korea to gain from this kind of move," Abe said. "This kind of attitude is meaningless." Abe said North Korea only will be accepted by the international society if it takes concrete steps toward complying with its commitment to dismantle its nuclear programs. This round of talks has been dogged by troubles since it started Monday, with Pyongyang refusing to take part for two days because of problems over the transfer of $25 million in North Korean funds frozen since 2005 at Banco Delta Asia in Macau under pressure from the United States. "This round of talks started with the BDA problem and ended with the BDA problem," Japanese envoy Kenichiro Sasae said. Banco Delta Asia was blacklisted by Washington on suspicion the funds were connected to money-laundering or counterfeiting. The North boycotted the international nuclear talks for more than a year over the issue. White House spokesman Tony Snow said the delay in the transfer of funds was the result of technical problems, and not unwillingness on the part of the United States. He did not elaborate on what those technical issues were, but said Washington hoped the mechanics of transferring the funds would not slow the nuclear talks. China had promised to resolve the issue as quickly as possible by transferring the funds to a North Korean account at the Bank of China. Officials said the Chinese bank held up the transfer because of worries that the money had been at the center of criminal investigations. "The Bank of China has concerns (about accepting the money) and not all the concerns have been assuaged," Chinese negotiator Wu Dawei said. Adding to the confusion over the matter, the Bank of China denied Thursday that it was told to accept the money. "I can tell you that up until now, we were not asked to deal with this business," Li Lihui, the bank's vice chairman and president, told reporters in Hong Kong. With details about the fund's transfer sketchy, various explanations have been offered by other parties. Russian envoy Alexander Losyukov, who also left for home Thursday, was quoted by ITAR-Tass news agency as saying "the whole problem came from the American side." He said the United States failed to assure the Chinese side that the Bank of China could receive the funds without fear of facing U.S. sanctions or a "negative attitude" from the banking community and the U.S. government. South Korea's Yonhap news agency said the money transfer was being delayed because Macau authorities were having difficulty confirming the ownership of 50 North Korean accounts, most of which are under the names of the heads of Zokwang Trading Co., a North Korean-run firm in Macau that U.S. officials have long suspected of being involved in money-laundering. "The difficulty of this issue is beyond our expectations and due to some technical and procedural issues we had not expected completely before," Chinese Foreign Ministry spokesman Liu Jianchao told a news conference. The six parties - the two Koreas, the United States, Russia, China and Japan - were in Beijing to discuss how to push forward the landmark deal in which Pyongyang agreed to start dismantling its nuclear facilities in exchange for energy and economic aid. Under the deal, the North is to receive energy and economic aid and a start toward normalizing relations with the U.S. and Japan, in return for beginning the disarmament process. The regime ultimately would receive assistance equivalent to 1 million tons of heavy fuel oil if it fully discloses and dismantles all its nuclear programs.