Two police officers alleged to have been recorded referring to an alleged victim of domestic abuse as a "slag" and "bitch" are under investigation.

The woman, Alex Faragher, says she discovered the abuse on her mobile phone voicemail. The two West Midlands police officers appear to have been unaware they had dialled the woman's phone and that their conversation had been recorded.

A senior West Midlands officer said the alleged incident may put off other women who have suffered violence from seeking protection from the police, and vowed a thorough investigation.

Faragher, 19, from Sutton Coldfield in the West Midlands, complained to police in January, alleging she had suffered domestic violence. The two officers had wanted to take a statement from Faragher but she was out.

On the recording, first reported by the Birmingham Mail, one officer allegedly says: "Fucking bitch, I specifically said: 'You are not going to give us the runaround are you?'"

Then the words "fucking slag" can allegedly be heard.

Chief Superintendent Rachel Jones, from West Midlands police, said she was shocked when she heard the recording: "My initial reaction was one of shock and of devastation, not least for the complainant but also for other victims of domestic abuse who may have reservations about coming to the police in the first instance.

"Clearly this won't do any good in terms of encouraging them to come forward."

The two officers have been placed on restricted duties. After consulting the Independent Police Complaints Commission, it was decided West Midlands police would investigate the incident.

Jones added: "This complaint is being professionally and robustly investigated and the force will take necessary action against officers if appropriate.

"I have visited the complainant personally to explain what action is being taken as well as apologising for any upset caused as a consequence of the officers' alleged conduct."

Polly Neate, chief executive of charity Women's Aid, said: "Domestic violence is caused by misogynism and derogatory attitudes towards women within society which makes some men feel it is acceptable to control and abuse their partners, and makes it hard for those women to escape.

"Our experience is that police officers can hold outdated and sexist attitudes towards women and especially women experiencing domestic violence."