An 11-year-old girl has been told off by police after being involved in a Facebook plot to encourage people to riot.
Devon and Cornwall Police said its officers visited the girl's home and spoke to her regarding a page on the social networking site which called people on to the streets of Plymouth during disturbances which took place in other parts of the country.
A force spokesman confirmed the girl was "given words of advice concerning entries on to social networking sites".
He said: "The force is also continuing to monitor social media sites and take action where appropriate to deal with potential to create disorder.
"A 20-year-old man from Torquay, three men in their 20s from Newquay and an 11-year-old girl in Plymouth have all received visits by police and been given words of advice concerning entries on to social networking sites.
"None of the entries led to any disorder taking place."
The page, Plymouth Riot Save Are England from the Goverment (sic), was listed as an "event" and invited more than 400 people to take part in pre-planned copycat disorder on Tuesday outside the city centre's Poundland store.
But while a handful of people, including Devon and Cornwall Police, confirmed their attendance online, nobody turned up.
The creator of the page, which has now been removed, was a man using the name Keith Hawkins. Before the page was taken down he was subjected to a barrage of abuse from local Facebook users who were alerted to its presence by friends and who were furious that he was planning such an event in the city.
Oliver Colvile, the Conservative MP for Plymouth Sutton and Devonport, said he was "horrified" that a girl as young as 11 had been involved in inciting violence.
He told the Plymouth Herald newspaper her actions were "appalling".
He said: "I have no doubt that the parents of this girl are horrified about what their daughter has done, as am I.
"Parents have got to take responsibility for their children's actions, and I would make sure that they and the girl know what the implications are.
"Investigating these sorts of things uses resources at a time when we simply cannot afford additional expenditure. It is costing the British taxpayer."
A 16-year-old youth, from Exeter, has also been spoken to by Devon and Cornwall officers over attempts to spark unrest in his home city.
Though there has been no unrest in Devon and Cornwall, the force, like others across the country, plans to continue with "high visibility" policing into the weekend, it said.