Leading members of the International Atomic Energy Agency have criticized North Korea's recent nuclear test and urged Pyongyang to return to disarmament talks.

Diplomats attending an IAEA board meeting in Vienna Wednesday say North Korea's May 25 nuclear test drew criticism from the United States, the European Union, China, Japan and Canada.

U.S. delegate Geoffrey Pyatt said Washington will not accept North Korea as a nuclear weapon state. He called on Pyongyang to return to six-nation talks aimed at giving the impoverished nation fuel and other benefits in return for dismantling its nuclear weapons program.

The leaders of Russia and China issued a separate joint statement Wednesday expressing "serious concern about the situation on the Korean peninsula."

At a meeting in Moscow, Russian President Dmitri Medvedev and his Chinese counterpart Hu Jintao called for the "swiftest possible resumption" of the six-party nuclear talks, which broke down earlier this year.

The two leaders' statement did not contain any new initiatives for reviving negotiations. The six nations involved in the talks are Russia, China, the United States, Japan, South Korea and North Korea.

U.S. President Barack Obama said Tuesday a nuclear-armed North Korea would be a "grave threat" to the world. He discussed the issue with visiting South Korean President Lee Myung-bak at the White House.

Mr. Obama promised to strictly enforce tougher sanctions on Pyongyang adopted by the U.N. Security Council. The council approved the sanctions in response to North Korea's latest nuclear test and test-firing of several missiles.

Japanese and South Korean media say Pyongyang appears to be preparing two sites for more long-range missile tests.

North Korea has lashed out at international criticism of its nuclear and missile tests by threatening to intensify its weapons programs.

Some information for this report was provided by AFP, AP and Reuters.