Pressure to bring thousands more criminals to justice has forced police to embark on a major cell-building programme to lock people up.

The Government has imposed a national target of 1.25m offences "brought to justice" by April 2008 -- meaning the total number of convictions or cautions secured by the CPS and police.

Thames Valley Chief Constable Peter Neyroud said the targets would mean about 40,000 people brought to justice across Thames Valley during 2007-08. This would result in an estimated 100,000 people a year going through the force's cells -- an increase of 20,000 prisoners over about four years.

As a result, the number of cells in Oxfordshire will increase from 40 to 66 over the next couple of years.

During 2003-4, there were 36,071 convictions and cautions across Thames Valley. That is 10 per cent more than the 2001-2 figure of 32,926.

There were 9,375 convictions and cautions in Oxfordshire last year.

Mr Neyroud said: "We are pushing very hard on increasing the arrests for violence -- particularly domestic violence."

The domestic violence unit at Cowley Police Station has been expanded to identify worrying cases early, and prevent the level of violence escalating.

Thames Valley now has 4,117 officers, its highest ever, and Mr Neyroud said the extra bobbies on the beat had resulted in more people being arrested.

Abingdon Police Station is set to have the largest custody suite in the area under the programme.

An additional 20 cells are to be built, bringing the total to 33. Work costing £2.4m is expected to start in 2006.

Banbury's custody area will undergo a £1.1m refurbishment early next year. Five new cells will bring its total to 11.

St Aldate's Police Station, which has 17 cells, will receive a £600,000 facelift to include CCTV during 2007. There will be no upgrade to the five cells at Witney.

The force is expected to need planning permission for much of the work it carries out.