Water fight! (This one in Columbia, Md.) (MARVIN JOSEPH/THE WASHINGTON POST)

Police say the 20-year-old has been charged with “encouraging or assisting in the commission of an offence” under the 2007 Serious Crime Act, the Guardian reports.

The arrest seemed to confirm fears that the British government is monitoring the BlackBerry Messenger service (BBM), a closed communications network favored by Britons in organizing last week’s riots in London and elsewhere.

During last Thursday’s parliamentary debate on the riots, Prime Minister David Cameron warned that the government would look at shutting down BBM if it was being used to “plot” crime. Member of Parliament Louise Mensch supported Cameron’s idea, comparing such a ban to closing a stretch of rail after an accident.

A police spokesman declined to disclose whether Essex police had been monitoring the service but said that the agency is using “appropriate measures” for the crime.

While the British government seems to see no problem prosecuting the organizing of water fights as a crime, the move puts it in the same camp as autocratic regimes such as Iran, where police arrested a number of people involved in a water fight this month.

On social news site Reddit, some readers reacted to the arrest with sarcasm, suggesting that the British government should “stop this at the source” by banning water altogether.

But another reader cautioned people to remember that an earlier water fight in Britain had turned violent, with one girl being punched in the face and gangs of people wielding knives joining in by the end of the event.

That water fight, which took place in London’s Hyde Park, had been organized on Facebook.

Th police were disperse that water fight but did not arrest anyone. This week’s arrest, then, marked a new and harsher response by the British government to petty crimes.