(Adds remarks by South Korean envoy)
By Stephanie Nebehay
GENEVA, Feb 27 (Reuters) - North Korea accused the United States on Wednesday of contributing to an "unpredictable" situation on the divided Korean peninsula and abusing its power in the U.N. Security Council to impose its "hostile policy" against Pyongyang.
North Korea is facing further United Nations sanctions for its underground nuclear test explosion two weeks ago, its biggest and most powerful to date which drew warnings from Washington and international condemnation.
In December it launched a long-range rocket in a move that critics said was designed to test technology for an intercontinental ballistic missile, leading to tighter U.N. sanctions being imposed last month.
"The U.S. is to blame for the situation on the Korean peninsula which is inching close to an unpredictable phase now," So Se Pyong, North Korea's ambassador in Geneva, told the U.N.-sponsored Conference on Disarmament.
A week ago, North Korea's delegation threatened South Korea with "final destruction" during a heated debate at the talks, the main U.N. disarmament negotiating forum.
U.S. ambassador Laura Kennedy did not respond to the verbal assault on Wednesday.
But South Korea's disarmament ambassador Kwon Haeryong took the floor to urge its isolated neighbour to "abandon its nuclear ambitions without delay and embark on the path to peace".
"North Korea's nuclear test is a challenge to the peace and security of the Korean peninsula and northeast Asia and beyond. There should be no mistake that the biggest victim will be none other than North Korea itself," Kwon said.
So, a former ambassador to Iran, retorted: "I'd like to give you objective advice that it will be much better for South Korea to keep quiet, pay more attention to your own concerns of internal affairs and demonstrate at least a little patience instead of making troubles and opening Pandora's boxes".
North and South Korea are technically still at war after their 1950-53 conflict ended in a truce, not a peace treaty.
So said he wanted to draw attention to the "intensified U.S. hostile policy" toward the Democratic People's Republic of Korea which has a right to launch satellites for peaceful purposes.
"The U.S. should no longer be allowed to seriously infringe upon the independent right of the DPRK to use space for peaceful purposes nor should it be allowed to abuse the U.N. Security Council as a tool for executing its hostile policy toward the DPRK," he declared.
The United States has launched the most military satellites and nuclear-capable intercontinental ballistic missiles in the world, he said, making it "the biggest threat to world peace".
North Korea's latest nuclear test, its third since 2006, had been a resolute step in self-defence, So said.
"The third nuclear test was carried out as part of the practical countermeasures for defending the country's sovereignty and security to cope with ruthless hostile behaviours of the U.S., which wantonly infringed upon the DPRK's legitimate right to satellite launch for peaceful purposes."
Ireland's foreign minister Eamon Gilmore said that North Korea, by defying U.N. resolutions, shunning its obligations under the nuclear Non-Proliferation Treaty (NPT), and refusing to cooperate with the IAEA nuclear watchdog, "only isolates itself further from the international community".
In a speech at the forum, he called on North Korea to cease immediately nuclear testing and ballistic missile activities and re-engage in stalled six-party talks on de-nuclearisation.
The talks involving the two Koreas, the United States, Japan and Russia are aimed at curbing Pyongyang's nuclear ambitions. (Reporting by Stephanie Nebehay; Editing by Jon Hemming)