North Korea yesterday said it would quit international nuclear disarmament talks and restart a plant that makes bomb-grade plutonium after the United Nations chastised it for launching a long-range rocket.

The UN Security Council on Monday unanimously condemned North Korea's launch on April 5 as contravening a UN ban, and demanded enforcement of existing sanctions against Pyongyang. Prickly North Korea said in a Foreign Ministry statement that the UN action and separate six-country nuclear talks were an infringement of its sovereignty and it "will never participate in the (nuclear) talks any longer nor... be bound to any agreement of the six-party talks".

The statement, carried by the official KCNA news agency, said North Korea would "bolster its nuclear deterrent for self-defence in every way", actively consider building its own light-water nuclear reactor, "revive nuclear facilities and reprocess used nuclear fuel rods".

Experts said the impoverished and energy-starved North lacks the technology to make an advanced light-water reactor.

Financial markets in Seoul and Tokyo were not affected by Pyongyang's announcement, with investors seeing it as more of the sabre rattling they have come to expect from the reclusive state. North Korea began taking apart its Soviet-era Yongbyon nuclear plant more than a year ago as a part of a disarmament-for-aid deal it reached with China, Japan, Russia, South Korea and the United States.

The UN response to a launch widely seen as a disguised test of a long-range missile will have little immediate impact on the North's faltering economy and the divided international reaction could embolden leader Kim Jong-il, analysts said.