Two men in northwestern England were handed stiff jail terms for inciting disorder during Britain's recent riots through social networking site Facebook.

Police in Britain have arrested more than 3,000 people over riots that erupted Aug. 6 in north London and flared for four nights across the capital and other English cities. The 1,000th person was charged in connection with the London incidents, police said Wednesday.

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A 12 year-old boy shields his face as he leaves Manchester magistrates' court after admitting burglary, during the recent riots in Manchester, northern England August 11, 2011. (Nigel Roddis/Reuters)

The huge numbers and public anger has sparked concerns that judges were handing out sentences that were disproportionate.

Cheshire Police said Jordan Blackshaw, 20, and Perry Sutcliffe-Keenan, 22, both received four-year sentences late Tuesday for using Facebook to "organize and orchestrate" disorder.

Blackshaw used the social networking site to create an event — with a date, time and location — for "massive Northwich lootin."'

Sutcliffe created a page on Facebook called "Warrington Riots" which listed a time and date for anyone who wished to be involved in a riot.

The sentences were defended by the Crown Prosecution Service, which said the efforts by the pair led to panic and revulsion among Cheshire residents.

Prime Minister David Cameron supported the sentences, when asked by reporters about them.

"What happened on our streets was absolutely appalling behaviour and to send a very clear message that it's wrong and won't be tolerated is what the criminal justice system should be doing," Cameron said in the Guardian newspaper.

"They decided in that court to send a tough sentence, send a tough message and I think it's very good that courts are able to do that."

Most of the convicted suspects have been sent for sentencing to higher courts, which have the power to impose longer terms of imprisonment. Two-thirds of the accused have not been granted bail.

The usual rate for the magistrates' courts hearing their cases is 10 per cent.

Some of the harsher sentences are expected to be appealed.

"It will be a further drag on the court system, which is already struggling — and that's before considering the pressures on the prison system," said Andrew Neilson of the Howard League for Penal Reform.

Acting London Metropolitan Police chief Tim Godwin issued a statement Wednesday urging the public to turn in anyone involved in the disorder.

"Don't let them get away with it," he said.