Shops selling human excrement began operating in North Korea this year, as acute shortages of fertiliser in the sanctions-wracked country put a price on faeces, an analyst said.

Aid groups have said human waste has long been used on domestic crops in the impoverished communist state, but there is now a trade in the readily available commodity, a North Korea analyst told a seminar at a South Korean university.

"Each household used to use human excrement as fertiliser. But because it's hard to keep up with the amount, 'human manure' shops showed up at markets," Kim Young-Soo, a professor at Seoul's Sogang University, told the seminar.

The lack of fertiliser has become acute since South Korea stopped annual shipments of rice and fertiliser to North Korea in 2008, amid worsening relations.

Professor Kim also said other products making their way on to a limited must-have list for North Koreans this year included skinny jeans, after a ban on fashionable trousers was lifted.

North Korean women have previously been told to wear only skirts or traditional attire in public places, but the interdiction on trousers was lifted this year, Professor Kim said.

"Skinny jeans are now popular and are changing the fashion style of women in Pyongyang," he said, citing sources in the hermit state.

Other popular items include secretly imported South Korean products like instant noodles and adult movies, he said.

North Korea is a tightly controlled society with foreign-made films or dramas heavily censored or banned because of their decadent "imperialist" culture.

Defectors say South Korea's pop culture is nevertheless popular in the isolated country.

Videotapes and CDs of South Korean films, music or TV soap operas enter mainly via neighbouring north-east China.

- AFP