"The Secretary-General condemns the underground nuclear weapon test conducted by [North Korea] today," Ban's spokesman Martin Nesirky said in a statement. "It is a clear and grave violation of the relevant Security Council resolutions."
In Moscow, a Foreign Ministry source struck a similar note, telling the Interfax news agency that Russia "decisively condemned" North Korea's nuclear test on Tuesday as a violation of Pyongyang's international obligations.
"We condemn these actions by North Korea and view them together with the ballistic rocket launch carried out earlier [in December] as a violation of the corresponding UN Security Council resolution," the ministry source said.
British Foreign Secretary William Hague also "strongly" condemned the nuclear test Tuesday, and said Britain would press for a robust response to the test by the Security Council.
"I strongly condemn this development, which is a violation of UN Security Council Resolutions 1718, 1874 and 2087," Hague said in a statement.
Meanwhile, the US Office of the Director of National Intelligence on Tuesday said only that intelligence agencies are aware of a "seismic event," which North Korea has claimed was the nuclear test.