North Korea came under heavy fire from the UN's atomic watchdog on Wednesday over the nuclear test it carried out last month.
At a meeting of the International Atomic Energy Agency's 35-member board in Vienna, a large number of member countries -- including the United States, China, Japan and Argentina -- all condemned Pyongyang's test on May 25.
The nuclear test and an earlier missile test were "serious, unacceptable and provocative acts," the US deputy chief of mission, Geoffrey Pyatt, told the closed-door meeting.
The US "will not accept North Korea as a nuclear weapons state," Pyatt added and called on Pyongyang "to return without condition to a process of peaceful dialogue and to honour its previous commitments to de-nuclearize the Korean Peninsula."
Other countries were also vocal in their condemnation, a diplomat who attended the meeting said.
Around 12 countries stood up to speak during the morning session.
The Czech Republic, speaking on behalf of the EU, said the test "profoundly jeopardizes regional stability and represents a severe threat to international peace and security."
The Chinese delegate said the international community needed to respect North Korea's sovereignty, but urged the Pyongyang regime to come back to the table "and the rest of us to show common restraint," according to the diplomat.
Japan described the test as a "grave threat that undermines peace and security in North East Asia", Canada condemned it as "irresponsible and provocative" and Argentina expressed "energetic condemnation" of the act.
At the start of this week's meeting, IAEA director general Mohamed ElBaradei had described the test as "a wrong step in the wrong direction which has again created an environment of confrontation."
North Korea ceased cooperation with the IAEA in mid-April, ordered the agency to remove all containment and surveillance equipment from the Yongbyon nuclear facilities and asked IAEA inspectors to leave the country.
Last week, the UN adopted a resolution against the hardline communist state after it tested a long-range missile and a nuclear bomb and stormed out of a six-nation disarmament agreement.
The resolution calls for tighter inspections of cargo suspected of containing banned missile and nuclear-related items, a stricter arms embargo and new targeted financial curbs to choke off revenue for North Korea's nuclear and missile sectors.
At the IAEA meeting on Wednesday, the Russian delegation said it felt the sanctions to be "balanced and fair", according to the diplomat.
In response to the new UN sanctions, Pyongyang vowed to turn all the plutonium it produces into bombs and to begin a separate weapons programme based on enriched uranium.
Speaking to reporters on the sidelines of the meeting, IAEA board chairwoman Taous Feroukhi said member countries had all insisted that the watchdog be involved in the process of verifying North Korea's nuclearisation, but the main focus at the moment was to persuade Pyongyang to return to six-party talks.