In a game where contestants travel all over London armed with water pistols looking to assassinate other players, police have condemned the game saying that it could spark terrorism alerts.

On its website, "StreetWars" is described as a three week long, 24/7, watergun assassination tournament and it begins on Tuesday in the capital.

The game, which has already taken place in cities such as New York, Los Angeles, Vancouver and Vienna, involves players hunting down targets whose details they have been given and then squirting them with water to eliminate them.

However, police state that the appearance of people behaving suspiciously, armed with what could look like real guns, risked sparking major alerts in a city where four suicide bombers attacked the transport system last year, killing 52 commuters.

British Transport Police said in a statement, "The sight of people carrying what appears to a be a firearm on the Tube one year after the tragic events of July 2005 will cause passengers and staff genuine fear."

Scotland Yard also poured cold water on the game, saying it could divert essential resources.

A spokesman said, "a seemingly innocent bit of fun can escalate with armed officers responding to what potentially is reported as a life-threatening situation."