Fion claims that last month she received a torrent of abuse from her supervisor, who called her a 'lazy and deranged freak' with a bad attitude and a penchant for trouble-making, because she did not know the directions to a remote village in the New Territories.

'The sergeant, a staunch Christian, sent me to investigate a prank caller abusing emergency telephone services on my own. This is very rare for a police officer, regardless of sex. But with me it wasn't even the first time.

'He seemed to take pleasure sending me on solitary assignments. When I told him I didn't know the way, he just erupted,' Fion said.

The outburst drove her to attempt suicide by flinging herself off the station's roof, but she was restrained by colleagues.

Fion was transferred from the investigations team to the DIS in March following her sex-change operation to minimise interaction with the public and risk offending sensibilities, an assessment Fion agreed with, she said.

But the section to which she was assigned, with a light workload and steady hours, has traditionally been reserved for 'shoe-shine boys who know the right people', and her transfer was perceived as favouritism for being a transsexual, she said.

'I was made to feel very unwelcome from day one,' Fion said. 'At first, they refused me access to the ladies toilet, then they moved my computer to another room. It was so insulting. You have to understand that in government departments it is very rare to rearrange an office because of inventories of equipment and the like. By moving the computer, everyone knew they just wanted me to leave.

'None of my colleagues would even talk to me. They didn't invite me to have tea in the canteen, shunned me at lunch time. It was as though I had a contagious disease.'

Then a series of unflattering letters circulated around the department, she said, and the station held 'counselling sessions' for female staff to discuss how to cope with a transsexual colleague. 'When I complained to my supervisor [a chief inspector] he told me to be a good girl, stop making such a fuss and that they were already bending backwards to accommodate me.

'It was almost like a warning,'

Following her suicide attempt in May she was transferred to the police force's Castle Peak division, where she has settled into her job with new colleagues who are 'very understanding'.

However, she plans to submit a complaint to the Equal Opportunities Commission if no formal action is taken against the supervising officers at the DIS.

'They tried to get me to resign, but I like my work and I won't give them the satisfaction. All I want is to be treated with fairness and respect, and for the sergeant and the chief inspector to be punished. Otherwise it will only happen again,' she said.

A police spokesman said: 'Generally speaking, we have a policy of equal opportunity and a policy of being a caring organisation.

'We encourage officers to look out for each other. If our officers encounter problems we encourage them to speak to our senior staff, and we also provide psychological counselling for officers who need assistance.'