He added he did not hear what was discussed during the meeting.

The three-day conference that ended Saturday had raised hope that US and North Korean officials could have meaningful discussions after the two sides' working-level nuclear talks in Sweden last month ended fruitlessly.

US Special Envoy for North Korea Mark Lambert participated in the conference, while Pyongyang sent Jo Chol-su, director-general of the North American affairs bureau at its foreign ministry, to attend. Seoul's top nuclear envoy, Lee Do-hoon also participated.

During a pre-conference reception on Thursday, Lambert and Jo spoke to each other for about five minutes, according to participants. It was unclear if the meeting Countryman was referring to is that brief encounter or a separate one-on-one meeting.

Commenting on the remarks by North Korean officials during the nonproliferation conference, Countryman said he did not hear "anything new."

"I heard the same old rhetoric from speakers, about hostile policy, about denuclearization of the entire world, about the peace-loving nature of the DPRK," he said. DPRK stands for North Korea's official name, the Democratic People's Republic of Korea.

During the conference, the Pyongyang official, Jo, called on the US to make a "forward-looking" decision by the end of the year -- the nuclear negotiation deadline set by North Korean leader Kim Jong-un.

"We have given considerably much time to the US, and we will wait for some results until the end of this year," Jo said.

"Though we expect everything to go into a positive direction, I want to say that the window for opportunity is closing bit by bit every day," he added. (Yonhap)