North Korea's collapse will be brought about not by external pressure or the economic malaise but by widespread crystal methamphetamine abuse, say North Korean defectors who have recently arrived in the South.

How serious the problem is can be gleaned from a special instruction issued by North Korean leader Kim Jong-il's son and heir Jong-un, who earlier this year ordered the security forces to round up drug users, "regardless of rank" -- implying that addiction is widespread in all strata of society.

Defectors say that youngsters at an elite school in Chongjin, North Hamgyong Province attended by the children of senior officials were caught by security officers having sex acts while watching a porn video under the influence of the drug. Widespread drug use has also been reported at major universities such as Pyongyang University of Foreign Studies and Kim Chaek University of Technology.

North Korean sources say many security officers are themselves in thrall to the highly addictive drug.

Rumors say that at an officers' school under the North Korean Army near the border area, senior officers are enticing female soldiers under their command to use the drug and siphoning off the school's food to raise money for drugs.

Many officials of the State Security Department, the key North Korean agency charged with protecting the regime, are drug abusers themselves, sources claim, and reportedly work themselves up into frenzies of violence under the influence.

Instead of disposing of drugs they confiscate, officials either use them themselves or make money selling them on.

Some North Koreans allegedly use drugs as currency, with high school students exchanging them as birthday gifts and people even giving them as wedding presents.

The drugs in circulation are made in the North. The North reportedly began producing them in the early 1980s to earn the hard currency for the regime.

But crackdowns abroad have made export more difficult, especially in China, so the drugs are now sold in the North itself.

Once the taboo was broken, drugs became rampant. Even scientists at academies of sciences have begun secretly making drugs in their laboratories to earn money on the side as the economy goes fr om bad to worse.

A former senior North Korean official who recently defected to South Korea said the number of drug addicts has soared since a botched currency reform in late 2009.

A rumor among senior officials in Pyongyang in recent days is that Kim Jong-il's younger sister Kyong-hui is among the addicts, and Kim father and son too use the drug.