North Korea has issued another warning, a day after announcing plans for a third nuclear test. In a statement, Pyongyang pledged "physical counter-measures" against South Korea if it participated in the UN sanctions regime, BBC News reported.

The threat came a day after North Korea said it was proceeding with plans for a "high-level" nuclear test.

The US has condemned the move, with the White House calling it "needlessly provocative".

North Korea has conducted two nuclear tests in the past, in 2006 and 2009. It gave no time-frame for its third test.

Its announcement followed the adoption by the UN Security Council of a resolution condemning North Korea's recent rocket launch and extending sanctions.

North Korea says its rocket launch was for the sole purpose of putting a satellite into orbit; the US and North Korea's neighbours say it was a test of long-range missile technology banned under UN resolutions.