The three broadcasters had to give the Metropolitan Police raw, unedited footage of the rioting and looting after Scotland Yard obtained a production order under the Police and Criminal Evidence Act 1984.
The Daily Telegraph is also understood to have disclosed its newsgathering material from the riots to the police after being served with a similar order.
The Times and The Guardian have consistently resisted police requests for footage, and it is not clear whether Independent News & Media, owner of The Independent, has been contacted as yet.
Police have been putting intense pressure on all media groups to reveal their video and picture evidence of the riots that engulfed England last month.
However, a senior insider at one of the broadcasters told The Guardian that it was rare for footage to be handed over in such a way.
"It is very very rare that we are served with a court order to hand over footage like this," the source said.
"We don't hand over material willy-nilly because it compromises the security of our journalists on the streets. Clearly we don't want them being seen as an evidence-gathering arm of the police."
A BBC spokeswoman said in a statement: "Police requests for BBC untransmitted material are dealt with through our legal department, regardless of the subject matter.
"We require requests for untransmitted material to be made through the courts. A production order requiring footage of the riots was served on the BBC and a court agreed that the material should be supplied."
An ITN spokesman said: "ITN's policy is that we do not release unbroadcast material to police. On some occasions when the police apply to a judge for a court order to force the release of such material, we have challenged the police's application."
A Sky News spokeswoman said: "Our standard policy is that we do not supply material to the police without a court order. On occasions - as has happened with some of our footage of the riots - where police request untransmitted material and an order is obtained we will comply with it."
Reporters and cameramen from the BBC, Sky and ITN were attacked while trying to cover the riots that blighted London seven weeks ago. A BBC radio car was also set on fire in Salford as the violence spread to the North of England.