A pair of so-called "paedophile hunters" have been arrested by police as officers begin a crackdown on social media vigilantes.

Police issued the warning after violence broke out in Bluewater shopping centre in Kent last week during a sting set up by a group known as The Hunted One.

Typically the group's volunteers would start chatting with online predators after posing as underage children online and would then stream live footage of members pouncing on suspected sexual predators.

But the sting descended into violence, and two people were charged with public order offences in connection with the disturbance at Bluewater Shopping Centre on Easter Sunday.