The 30-year-old man, identified only by his surname Park, was accused of spreading false information on an Internet discussion site last month that the government ordered major financial institutions and trade businesses not to purchase dollars.

Park was detained on Wednesday and has admitted to the allegations, prosecution spokesman Oh Se In said. An arrest warrant is being sought, said an official with the prosecution's investigation team, who spoke on condition of anonymity citing department policy.

In about 100 postings on the popular website last year, Park criticised the government's handling of the economy and made predictions, largely negative, on the future. His writings were sprinkled with jargon that convinced some readers he was an economic expert.

Park - known widely by his pen name 'Minerva', the mythological Greek goddess of wisdom - described himself in Web entries as a former securities firm worker with a masters' degree earned in the United States and an experience in the field of corporate acquisitions and takeovers, according to local media.

But prosecutors found that Park was an unemployed resident of Seoul who studied economics on his own after graduating from an vocational high school and a junior college with a major of information and communication, Oh said.

Some newspapers have raised speculation that Park might not be the 'real Minerva', suggesting that he could have simply helped somebody else post articles under his Web name.

But Oh said prosecutors believe that is not the case.

Many of Park's purported articles were written in an acrimonious way, often with offensive language, especially when criticising government policies. Predictions were often specific, such as the South Korean won would fall to a specific level 'tomorrow'. And some predictions proved correct, including an October forecast that the Korean currency would depreciate to 1,400 won against a dollar.

According to media reports, Park also predicted Lehman Brothers would topple after Seoul's state-run Korea Development Bank withdrew its attempt to acquire a stake in the US investment bank in September.

His deeply analytical style and sometimes prescient forecasts made him a star on the Web, earning him the nickname 'economic president on the Internet'. Still, he has remained hidden from public view, fueling speculation about his identity.

One leading monthly magazine even carried what it claimed was an article by 'Minerva', and an apparently written interview with him in December in which he claimed to have worked at a securities company. He also said he had lived abroad before, and that his predictions were based on his experience and information publicly available.

He also told the magazine that he would not write on the economy any more, saying he does not want publicity.

'I don't think it is necessary to identify myself because I haven't written to rise to stardom,' he said in the interview, describing himself as an 'old man'. -- AP