North Korea will probably test a nuclear weapon, with an even chance of doing so this year, as Kim Jong-il’s regime tries to assert its defiance in the face of increasing international pressure, said Richard Armitage, former US deputy secretary of state.

Mr Armitage, who is urging Washington to talk directly to Pyongyang to try and resolve the nuclear stand-off, estimated there was a 50 per cent chance of a test by the end of the year.