A transgender police officer is suing her force after she allegedly had to “out” herself over a police radio system.

PC Emma Chapman claims Essex Police failed to help its officers understand transgender issues and properly investigate what had happened.

PC Chapman said that after initially telling people about her transition, she became “frustrated” at the lack of support and understanding. She eventually “stepped away” from being “open” and dealing with transgender issues in 2009.

According to legal documents seen by the BBC, her claim centres on three incidents when she had to speak to the police force’s control room via her radio handset.

The 44-year-old alleges that on the first occasion, in October 2012, the operator did not believe who she was, saying she had a “male voice”.

In her witness statement, the police constable said: “I felt a combination of alarm and distress.

“I replied… ‘I am a transsexual’.

“I felt very embarrassed and desperate. The incident took my breath away.”

Two further alleged incidents occurred in June 2013 when the officer was again challenged by control room staff who questioned her identity.

“I felt a growing sense of apprehension whenever I had to use the radio, concerned that there may be further, similar incidents,” she said.

“The radio is also a lifeline at times and I should not have to feel hesitant or anxious about using it.”

Essex Police said it “disagreed” with PC Chapman’s assertions and was contesting the case.

A spokesman acknowledged that conversations between PC Chapman and the control room had taken place but said the force disputed the “precise wording and tone” said to have been used.

The case was heard at the East London Tribunal Court last week after PC Chapman turned down an out-of-court settlement.

A decision is expected in the next few months.