"The six-party talks are over," Ri Hung Sik, spokesman for the North Korean delegation at a major Asian security conference, said Thursday.
North Korea's six-party negotiations with the U.S., Russia, China, Japan and South Korea ended last year after Pyongyang went back on a promise to halt its nuclear program.
Secretary of State Hillary Rodham Clinton, also attending the Association of Southeast Asian Nations, or ASEAN, conference in Thailand, urged Asian nations to vigorously enforce the latest U.N. sanctions against North Korea. She said Washington would pursue "every avenue" to denuclearize the Korean peninsula.
CBS News producer Jeff Goldman reports that a North Korean delegation attempted to take the podium Thursday to speak to reporters gathered for a scheduled news conference by Clinton before she arrived. They were turned away by ASEAN officials.
It was not immediately clear if North Korea's decision to declare it's participation in the six-party talks was made before or after the incident.
In remarks to ASEAN delegates, Clinton lamented the suffering of North Korea's people while stressing her view that the most urgent security issue in Asia is North Korea's illicit nuclear program.
"North Korea must end its pursuit of nuclear weapons and fulfill its pledges" to verifiably dismantle its nuclear arms production complex, she said, according to a text of her prepared remarks. "North Korea's response in turn has been more threatening behavior."
She called on the international community to implement the U.N. sanctions that are intended to deny North Korean ships access to ports for shipping banned cargo and to cooperate in enforcing financial sanctions against designated firms that support North Korea's nuclear program.
North Korea's Foreign Ministry, bristling at an earlier Clinton comment likening the regime to "small children" demanding attention, released a statement Thursday saying: "We cannot but regard Mrs. Clinton as a funny lady as she likes to utter such rhetoric, unaware of the elementary etiquette in the international community. Sometimes she looks like a primary schoolgirl and sometimes a pensioner going shopping."
Clinton said Wednesday at the ASEAN conference that North Korea's only viable option was "."
She said China, Japan, Russia and South Korea were all in agreement with Washington on this goal and were in a "strong position" in their dealings with the North Koreans.
She spoke at a news conference Wednesday after bilateral talks with foreign ministers of the four countries.