Russia had in December expressed "deep regret" over a long-range rocket launch by North Korea which Pyongyang said was a purely scientific mission aimed at putting a satellite into space.The RIA Novosti news agency said seismologists at the Russian Academy of Sciences had detected the small earthquake that was triggered by the nuclear test.

However Russia s chief sanitary doctor Gennady Onishchenko said that radiation levels in the Far East of Russia neighbouring North Korea were normal, Interfax said.North Korea confirmed Tuesday it had successfully carried out an underground nuclear test of a new, "miniaturised" device in what it called a targeted response to US "hostility".