The United States and the European Union sharply criticised North Korea on Wednesday as the board of the UN atomic agency was briefed on Pyongyang's nuclear activities.

The International Atomic Energy Agency (IAEA)'s latest report "is testimony to the long history of the DPRK (North Korea)'s lack of cooperation with the agency," a US statement to the meeting in Vienna said.

Washington shared the "serious concern" of the IAEA regarding North Korea's nuclear activities, in particular the disclosure last November of a uranium enrichment programme and construction of a light-water reactor.

"We, too, find these developments deeply troubling, particularly in light of North Korea's pursuit of a nuclear weapons capability and its long track record of proliferation -- to and from the DPRK," it said.

The EU expressed its "grave concern" at North Korea's decision to cease all cooperation with the IAEA, whose inspectors were kicked out in 2009, leaving the agency to rely on information from other sources and satellite images.

Pyongyang abandoned six-party talks -- grouping China, Japan, the United States, the two Koreas and Russia -- aimed at scrapping its nuclear arsenal in April 2009 and conducted its second nuclear test a month later.

But diplomatic efforts to restart the dialogue have picked up in recent months, with nuclear envoys from the two Koreas holding a rare meeting in Bali in July followed the same month by bilateral US-North Korea talks in New York.

Last month North Korean leader Kim Jong-Il held his first summit with Russian President Dmitry Medvedev in Siberia, and voiced hopes for the resumption of the so-called six-party nuclear disarmament talks.

The meeting ended with a Kremlin announcement that North Korea was ready to resume dialogue without preconditions and abandon atomic enrichment and testing once the six-party talks restarted.

But both the United States and South Korea dismissed the proposal as nothing new.

The US statement Wednesday at the IAEA said North Korea had to "demonstrate its seriousness on denuclearization, through substantive actions prior to the resumption of six-party talks."

Washington was "not interested in negotiations for the sake of simply talking."