Six youths have been arrested for allegedly attacking singer Lily Allen after a snowball fight in London turned nasty.

The Smile hitmaker was enjoying a day of winter fun at the city's Primrose Hill park on Monday, playing in the snow and sledding with a group of friends.

Allen was earlier photographed laughing and joking with the paparazzi - even trading a few handfuls of snow with the snappers.

But during the afternoon, a gang of six youngsters began pelting the star with snowballs, and the innocent game soon turned violent, forcing Allen to call police and flee with her bodyguard, according to London's Evening Standard newspaper.

A source tells the publication, "She took it in good spirits at first, but it got more relentless. Some people told the gang to stop before people started squaring up to them."

One man was said to have been badly beaten during the incident.

(This news article provided by World Entertainment News Network)