President Vladimir Putin said North Korea's nuclear test on Monday was a blow to global efforts to prevent proliferation of weapons of mass destruction.

"Russia unconditionally condemns the test carried out by the Korean People's Democratic Republic," Putin said.

"This is not just about Korea itself. We're talking about huge damage to the process of non-proliferation of weapons of mass destruction in the world," Putin said in comments broadcast on state television.

His comments came after Russian Defence Minister Sergei Ivanov gave an estimate of the size of Monday's blast higher than the assessment of experts in South Korea.

"Today at 0535 and 26 seconds Moscow time (0135 GMT) the ministry of defence's technical equipment recorded the carrying out of an underground nuclear explosion by North Korea," Ivanov said at a meeting with Putin.

"The power of the test was between five and 15 kilotons.... We also know precisely where the test occurred," Ivanov said.

If the blast was at the higher end of Ivanov's estimate, it exceeded in strength the US atomic bomb which destroyed Hiroshima during World War II -- comparable to 12,500 tonnes of TNT.

Earlier in Seoul the head of the Korea Earthquake Research Centre gave a more modest estimate of the size of the blast, saying the activity measured 3.6 on the Richter scale, which could be caused by the explosion of the equivalent of 800 tonnes of dynamite.

Putin said Russia would be consulting with the United Nations Security Council on the test with a view to trying to get North Korea's secretive regime back to the negotiating table.

"I hope that North Korea will return to the talks process and I have instructed the foreign minister to conduct consultations on this point with the UN Security Council," Putin said.

Pyongyang carried out the underground blast in defiance of international efforts to keep the secretive regime from becoming one of the world's nuclear powers.

Russia is a member of the six-party talks process that has been trying to dissuade North Korea from pursuing its nuclear ambitions.

The Russian foreign ministry said it had summoned North Korea's ambassador to voice its concern.

At the meeting, Deputy Foreign Minister Alexander Alexeyev "expressed deep regret and serious concern by the Russian side," a foreign ministry statement said.

"Such an act, carried out despite calls by the world community, leads to a further escalation of tensions on the Korean peninsula, damage to the international non-proliferation regime and provokes a nuclear arms race" in the region, the statement said.

In another statement the foreign ministry demanded that "North Korea promptly take steps toward returning to the nuclear non-proliferation treaty regime (NNPT) and restarting six-way talks. We will present this position to the UN Security Council".

But the ministry also urged a measured response from the world community.

"The Russian ministry of foreign affairs calls on all states involved in the current complex situation to show reserve and restraint," the ministry said.

Russia's reaction came as numerous other states, including Britain, India, Japan, Pakistan, South Korea and the United States, issued sharply worded condemnations of the test.

North Korea was a member of the NNPT, an international agreement forbidding the acquisition and proliferation of nuclear weapons, until 2003, when it withdrew from the treaty.

Six-sided talks on Pyongyang's nuclear program -- among North Korea, South Korea, China, Russia, Japan and the United States -- started in 2003, but stalled in November 2005.

Pyongyang's nuclear test came just three days after a unanimous call from the UN Security Council, for North Korea to abandon plans for testing a nuclear weapon.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.