A teenager questioned over violence which broke out during the tuition fee protests in London last week has been released on bail.
The 17-year-old boy was arrested on Saturday on suspicion of violent disorder and is due to return to a police station in mid-February.
He was the 57th person to be arrested since the demonstration on Wednesday.
On Friday, a 23-year-old student held after a fire extinguisher was thrown from a roof was released on bail.
The man, who comes from Reading and studies at Anglia Ruskin University, in Cambridge, was questioned on suspicion of violent disorder.
A group emerged on the roof of 30 Millbank, in central London, and demonstrators surged into the building, which is the Conservative Party's headquarters, during the protest.
Windows were smashed, fires lit and missiles hurled at police.