Tens of thousands of people have gathered in a snowy Pyongyang square as North Korean officials rally support for the country's recent nuclear test.

North Korean leader Kim Jong Un did not appear at the rally on Thursday. Workers' Party secretary Kim Ki Nam told the crowd that Tuesday's nuclear test, the country's third, was a self-defensive measure against US hostility.

The United Nations Security Council and Washington say the test violated UN resolutions.

North Korea is believed to be trying to develop nuclear-armed missiles.

In December, North Korea launched a satellite into space using a long-range rocket.

The UN and Washington said the launch was a test of banned ballistic missile technology and imposed tightened sanctions against the North.

North Korea conducted two previous nuclear tests in 2006 and 2009.