'Let's begin 2016 with thrilling sound'

North Korean leader Kim Jong-Un personally signed the order three weeks ago authorising Pyongyang's latest nuclear test, calling for 2016 to kick off with the "thrilling sound" of a hydrogen bomb explosion.

The North yesterday said it had conducted its first "successful" miniaturised hydrogen bomb test -- a shock announcement that drew condemnation from its neighbours including its major ally China.

The news was broadcast on state television, which also showed a copy of Kim's initial signed order dated December 15.

"Let's begin the year of 2016 ... with the thrilling sound of our first hydrogen bomb explosion, so that the whole world will look up to our socialist, nuclear-armed republic and the great Workers' Party of Korea!" Kim wrote in a handwritten message next to his signature.

The television also showed a second order dated January 3 in which Kim signed off his final approval for the test to be conducted on January 6.

Kim, who took over after the death of his father Kim Jong-Il in December 2011, also presided over the country's third nuclear test in February 2013.

Kim had suggested last month Pyongyang had already developed such an H-bomb -- a claim that was largely dismissed as exaggerated rhetoric at the time.

Experts say, with the surprise test two days before his birthday, Kim Jong-Un has once again asserted his personal control over the hermit state .

When he came to power after Kim Jong-Il's death in December 2011, the younger Kim was considered untested, vulnerable and likely to be manipulated by senior figures.

But he has proved his metal in dealing harshly -- sometimes brutally -- with any sign of internal dissent, even at the highest levels, while maintaining an aggressively provocative stance with the international community.