Oxford's network of street cameras has clocked up 659 arrests since it was launched two years ago.

Between February 1 and May 9, the 17 CCTV cameras in the city centre helped police arrest 98 people. They have also helped to find four missing people since 1999.

The system has been so successful that the Home Office has agreed to spend £60,000 on four more cameras covering Park End Street, Worcester Street car park and Worcester Street South. These will become operational within the next two months.

The Government is still considering bids for money to extend the scheme into the Friar's Entry area and the streets around St Ebbes and Turnagain Lane.

Sgt William Boyle said the cameras were invaluable in the fight against crime.

He said: "A proportion of these arrests would not have been made without the assistance of CCTV.

"They are a great invention and help us amazingly.

"They are also important because they give us an indication of what is happening in the city. We use them for all aspects of policing."

Sgt Boyle added: "If someone has been a victim of crime, they should contact us, because we may find something on the cameras. Before, finding witnesses could always be a problem."

The scheme is run jointly by Oxford City Council and Thames Valley Police, with the control room in St Aldate's police station. The aim is a have a 32-camera system covering the city centre by the end of this year.