The UN's atomic watchdog also criticised the North Korean nuclear test.
"The International Atomic Energy Agency remains ready to contribute to the peaceful resolution of the DPRK nuclear issue by resuming its nuclear verification activities in the country as soon as the political agreement is reached among countries concerned," IAEA Director-General Yukiya Amano said.
"It constitutes a clear threat to international peace and security and challenges efforts to strengthen global nuclear disarmament and non-proliferation. I am gravely concerned by this action, which deserves universal condemnation," executive secretary of the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organisation, Tibor Toth said.
"North Korea's future security and prosperity can only be secured through constructive relations with its neighbours and the international community," Australian Prime Minister Julia Gillard said.
Pakistan regretted the atomic test conducted by North Korea.
"Pakistan regrets that the government of DPRK has conducted an underground nuclear test today," Foreign Office spokesman Moazzam Khan said in a brief statement.
He said Pakistan "believes that all countries should comply with their respective international obligations".
Disgraced scientist A Q Khan, considered the father of Pakistan's nuclear bomb, played a key role in the illegal transfer of atomic technology and equipment, including centrifuges used to enrich uranium, to North Korea.