SEOUL, South Korea, Oct 9, SPA -- North Korea said Monday it performed its first-ever nuclear weapons test, claiming it set off a successful underground blast in a «great leap forward» that defied international warnings against the communist regime. The reported nuclear test sparked condemnation fromregional powers who said that, if confirmed, it would be aserious threat to regional stability. The U.S. called forimmediate U.N. Security Council action. The North's official Korean Central News Agency said the underground test was performed successfully «withindigenous wisdom and technology 100 percent,» and that no radiation leaked from that test site. «It marks a historic event as it greatly encouraged andpleased the (Korean People's Army) and people that havewished to have powerful self-reliant defense capability,»KCNA said, adding this was «a stirring time when all thepeople of the country are making a great leap forward inthe building of a great prosperous powerful socialistnation.» A top Russian military officer confirmed the device tested by North Korea was a nuclear weapon. Russian military monitoring systems «detected the test of a nuclear weapon in North Korea,» Russia's ITAR-Tass news agency quoted Lt. Gen. Vladimir Verkhovtsev as saying. «It is 100 percent (certain) that it was an undergroundnuclear explosion,» the agency quoted Verkhovtsev, thehead of a Defense Ministry department, as saying. An official at South Korea's seismic monitoring centerconfirmed that a magnitude 3.6 tremor felt at the time ofalleged North Korea nuclear test wasn't a naturaloccurrence. The official spoke to The Associated Press oncondition his name not be used, because he wasn'tauthorized to talk about the sensitive information to themedia. The U.S. Geological Survey said it recorded a seismicevent with a preliminary magnitude of 4.2 in northeasternNorth Korea that coincided with the country's announcednuclear test. The Colorado-based agency was unable to tell whether the event was the result of an atomic explosion or a natural earthquake, USGS official Bruce Presgrave said. The size of the tremor could indicate an explosiveequivalent to 550 tons of TNT, said Park Chang-soo,spokesman at the Korea Institute of Geoscience and Mineral Resources _ which would be far smaller than the nuclear bombs the U.S. dropped on Japan in World War II. The atomic bomb that struck Hiroshima, Japan on Aug. 6, 1945, had the destructive power of about 15,000 tons (33million pounds) of TNT. If the test is confirmed, the North would be the ninthcountry in the world known to have nuclear weapons. Theother countries are the United States, Russia, France,China, Britain, India, Pakistan and Israel. The White House said U.S. and South Korean intelligence had detected a seismic event at a suspected nuclear test site in North Korea. «A North Korean nuclear test would constitute aprovocative act in defiance of the will of theinternational community and of our call to refrain fromactions that would aggravate tensions in Northeast Asia,»White House spokesman Tony Snow said. «We expect the U.N. Security Council to take immediateactions to respond to this unprovoked act,» Snow said.«The United States is closely monitoring the situation andreaffirms its commitment to protect and defend our alliesin the region.»--SPA www.spa.gov.sa/395006