The Facebook group "Panic buy carrots", which already has over 236,000 members, is urging people to go out and buy the orange vegetable on May 15 "just for a laugh".

An opposing group, calling themselves "Don't add to world hunger! Don't panic buy carrots!", had only attracted 152 members by Thursday morning.

A message from the anti-carrot buying group originator states: "If you see anyone irresponsibly filling a shopping trolley with copious amounts of carrots, stop them and question them as to why they need to buy so many carrots."

Several other spin-off groups have been started including one called: "On May 16th 2008, everyone needs to go out and GIVE carrots."

A spokesman for the supermarket chain Asda, whose prize draw is featured on the www.panicbuyers.co.nr website, said: "We welcome people through our doors to buy carrots or anything else.

"We don't think this will lead to a shortage of carrots. And I don't think we would reorder any with this in mind."

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