North Korea on Saturday boasted of a newly developed anti-tank weapon that its leader said was so powerful it could turn the most heavily armoured enemy tanks into "boiled pumpkin".

Pyongyang's state media said leader Kim Jong-Un had watched tests of the portable, laser-guided rocket and declared it had the "longest firing range in the world", and was "as accurate as a sniper's rifle".

"He noted with great satisfaction that even the special armoured tanks and cars of the enemies which boast their high manoeuvrability and striking power are no more than a boiled pumpkin before the anti-tank guided weapon", the KCNA news agency.

Kim called for the weapon to go into mass production as soon as possible and for it to be deployed to frontline units and coastal defence units.

With a siege mentality bordering on paranoia, North Korea maintains a huge military. It has some 1.2 million active troops out of a population of around 25 million -- double the size of the armed forces in South Korea, which has twice as many people.

But most of North Korea's weapons are outdated and the military is seriously hamstrung by the impoverished state's chronic fuel shortages.

The shortages are likely to worsen when the country is slapped with tough new sanctions the United Nations is now weighing over a nuclear test and long-range rocket launch Pyongyang conducted earlier this year.

The UN Security Council sanctions include a ban on the supply of aviation fuel to North Korea.