This can't be right can it?

I have an under-performer within my team; he often makes careless mistakes and blames others when the mistake is discovered. I have spoken to him on numerous occasions about his performance but each time he becomes defensive and accuses me of picking on him. Things came to a head yesterday when he ‘lost it’ with another team members, accusing them of a mistake that he had quite obviously caused.
When I called him into the office to discuss the situation he again immediately became confrontational, and refused to discuss the matter. With that I immediately terminated any further discussions and referred the matter to a disciplinary interview, outlining his rights accordingly.

When I informed my HR Manager of what had happened she said I had no right to refer the matter to a disciplinary interview as a formal fact-finding exercise had not been completed. When I said that I had numerous facts relating to his poor performance/behaviour she informed me that if that was the case then I was not allowed to conduct the disciplinary as I had conducted the fact find. I know have to write a full report on the matter, copy it six times (My Boss, employee, HR Manager, Manager who is to conduct the interview, note taker and one copy for the file) I also have been told I am not allowed to brief the colleague who is to conduct the meeting as this would be seen as biased.

When I said this was not a gross misconduct issue and was way over the top my HR Manager said it was the law.

Is she correct?

Martin Pedley