A senior North Korean official on Tuesday threatened the United States, South Korea and Japan with a "nuclear catastrophe," accusing them of demanding Pyongyang first take concrete steps to reopen stalled multilateral nuclear talks.

Kim Tae-gil, a senior researcher at the North's foreign ministry-affiliated Disarmament and Peace Institute, made the outburst at an international conference in Tianjin, organized by the China Foundation for International Studies (CFIS) and the China International Institute for Strategic Society.

"There is neither confidence nor dialogue on the Korean Peninsula. What you see on the Korean Peninsula are hostile relations between the DPRK (North Korea) and the United States, together with distrust and confrontation between the North and the South of Korea," Kim said in his speech at the conference.

"If a crisis erupts on the Korean Peninsula, it would result

(in) a nuclear catastrophe and this catastrophe would engulf the United States, South Korea and Japan," Kim said in the English-language speech.

The six-party talks, which involved the two Koreas, the U.S., China, Russia and Japan, have been dormant since late 2008. Since conducting its third nuclear test in February, North Korea has repeatedly expressed its willingness to rejoin the six-party process "without preconditions."

South Korea and the U.S. have been demanding North Korea to show its sincerity by first taking steps to denuclearize itself.

China has been more accommodating toward North Korea, urging South Korea and the U.S. to lower the bar for Pyongyang to sit down at the negotiating table.

"The key principle of resolving the denuclearization issue on the Korean Peninsula is to set up a peace mechanism and deal with nuclear issues on the basis of the principle of action-for-action," Kim said.

"That is why the DPRK insists on resuming the six-party talks without any preconditions, rather than a resumption of talks with conditions that we make the first move unilaterally," Kim said.

"However, the U.S. refused to resume the talks and continued to step up its military threats against the DPRK," he said.

"Thus, the DPRK is compelled to strengthen its nuclear deterrent in order to safeguard its sovereignty. It is an inevitable choice," Kim said.

Launched in 2003, the six-party talks have yielded little progress in persuading North Korea to give up its nuclear ambitions. After conducting its third and most powerful nuclear test early this year, North Korea enshrined its nuclear status in its constitution.

While making diplomatic overtures, North Korea was confirmed last month to have restarted a nuclear reactor at its Yongbyon nuclear center. It is a provocative move that would provide Pyongyang with enough plutonium to build one atomic bomb a year.

During the conference, Kim made no mention of the restart of the plutonium reactor, but renewed calls for a peace treaty with the U.S. to eventually resolve a nuclear standoff.

"The frustration over the denuclearization of the Korean Peninsula is attributable to a lack of progress in efforts to set up a peace mechanism on the Korean Peninsula," Kim said.

"The peace mechanism should either precede or at least be parallel with the denuclearization process," he said. "That has been not the case so far."

The two Koreas remain technically at war after the 1950-53 Korean War ended in an armistice, not a peace treaty. About 28,500 U.S. soldiers are stationed in South Korea to stand as a defense against the North Korean threat. (Yonhap News)