Speed cameras in Sussex will not be able to enforce new 20mph limits set for the county, The Argus can reveal.

Fixed Gatso cameras, the type used on most roads, are not approved by the Home Office to operate below 30mph, Sussex Safer Roads Partnership admitted on Friday, March 22.

20mph limits will come into effect in Brighton and Hove on April 8, covering most residential and shopping streets in the city centre.

But as the limits are rolled out across the city over the next three years, speed cameras could become powerless to catch some offenders – and only able to catch those going at least 10mph over the new limit.

A Brighton and Hove City Council spokesman said the exact roads affected by the later phases were still subject to consultation so it is uncertain at this stage which cameras will be affected by the changes.

However the Coldean Lane camera currently set at 40mph and the 30mph device in Eastern Road are due to be part of the scheme.

The council has confirmed that other key roads that currently have cameras - including the A259 seafront road, Old Shoreham Road, New Church Road, Ditchling Road, London Road and Lewes Road - will be excluded from the 20mph limit.

A spokesman from Sussex Safer Roads Partnership, which operates the cameras, said although there were types of cameras that could be used to detect those breaking the lower speed limits, there were none in the county.

He said: “In some cases it may be necessary to install traffic calming features to help lower speeds but it is unlikely that the public would accept camera enforcement as the primary method of speed control.”

Sussex Police said while it will not routinely enforce the 20mph limits, offenders could be prosecuted if caught on hand-held speed guns or on footage recorded by cameras inside patrol cars.

Ian Davey, the chair of the council’s transport committee, said: “20mph limits are designed to be self enforcing. Average speeds across the area involved are already below 24mph and we expect drivers to play their part in improving safety by complying with the limits.”

Tom Scanlon, the city’s director of public health, said he hoped reducing speed limits would improve air quality and encourage people to get fit by walking or cycling.