Tens of thousands of young internet-obsessed South Koreans, whipped into a frenzy by alarmist television programmes, a complex scientific paper on genetics and a hyperactive online rumour-mill, have held candlelit vigils protesting against imports of American beef.

Believing that the meat carries a high risk of BSE and that Koreans are genetically predisposed to contracting the linked Creutzfeldt-Jakob disease, the online masses have taken to the streets, cursing America and demanding that their Government should act to avert catastrophe.

Two features of the protests have caught the authorities, the Government and teachers offguard.

The first is that, unlike the mobs that have contributed to South Korea's long history of street rallies, more than half of the demonstrators are below university age.

Some teachers approve of the rallies, others condemn them, but all agree that their students are spending too much time in cyberspace.

The second is the virulence of the xenophobia on and offline: despite sweeping to power on a more foreigner-friendly ticket, Lee Myung Bak, South Korea's new President, leads a country with substantial anti-American feeling.

Behind the fury and panic is the decision made last month by Mr Lee to allow US-produced beef back into the country after a five-year hiatus.

South Korea, with other Asian nations, suspended imports in 2003 after cattle in the US were found to have BSE: the protesters are convinced that the ban has been lifted too soon and with too many concessions to Washington.

On the many new BSE-related websites that have sprung-up in the last week, the language is little short of hysterical. Pseudo-science, anti-Americanism and teenage angst have produced a staggering volume of web traffic.

“Are we fated to die so young?” wailed a typical post. “I just want to live and fulfill my career dreams, not die mad like an American cow,” wrote another.

Over the past couple of days, virtually every teenager in Seoul has received the same text message on mobile phones, “Schools closed next Thursday”.

The information is bogus, but authorities are steeling themselves for street demonstrations on the grandest scale. By the weekend the protesters' numbers are expected to rise tenfold.

The BSE scare has already made its practical effects felt. After a two month honeymoon period in power, Mr Lee has approval ratings below 30 per cent.

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