Domestic violence officers in Oxford are struggling to deal with up to 60 answer-phone messages each night, putting pressure on response times.

The Oxford domestic violence unit is staffed by two officers based at Cowley police station, but many calls come in overnight, creating a backlog.

Pc Bill Pennington, of the Oxford unit, said: "We're coming to work in the morning and having to deal with at least 30 calls each on our answer machines. There are times when there could be a 24-hour delay in response."

The target is to respond to non-urgent calls within 24 hours, but the sheer volume of calls could hamper response times.

Thames Valley Police force is the only agency in Oxfordshire providing a 24-hour service dedicated to dealing with victims. In addition to the two Oxford-based officers, two officers in Banbury cover calls from north Oxfordshire, and three based in Wallingford cover calls from south Oxfordshire.

Nancy Hunt, the domestic violence response co-ordinator in Oxfordshire, said calls could increase dramatically in the next few months as people become aware of the range of support services available.

Pc Di Shepherd, from the Banbury unit, said: "We have about 10 referrals a day from police, and two or three self-referrals from people wanting advice." Chief Insp Judith Johnson, from the Cowley-based child protection and sex crimes unit, said a new system would be introduced next year to handle non-emergency calls.

She added: "We are in a state of change at the moment, so our performance around response times is dropping. If in doubt, victims should call 999."