North Korea appears to be preparing for a third nuclear test. A South Korean newspaper said today the US satellites detected movements of personnel and vehicles at the location where Pyongyang carried out its first two nuclear tests. But a South Korean defence ministry official told AFP on condition of anonymity that such movements were being constantly detected, possibly for the daily maintenance of keystrategic facilities there. North Korea conducted its first nuclear test in October 2006 and a second in May 2009 in Punggye-ri in the north-eastern province of North Hamgyong, the month after it walked out of six-party nuclear disarmament talks. China, the North's sole major ally and economic lifeline, is pressing to restart the six-party forum, which groups thetwo Koreas, the United States, China, Japan and Russia.