Mr Gaubert said he suffered severe post-traumatic stress

Nicholas Gaubert has described how the incident happened in July 2005, just a week before the fatal shooting of Brazilian man Jean Charles de Menezes.

Mr Gaubert, 34, said he was suffering severe post-traumatic stress as a result of the shooting.

The Independent Police Complaints Commission (IPCC) is investigating.

Mr Gaubert, who lives in Leeds, said he had now decided to speak out after the Crown Prosecution Service ruled no officers involved should be charged with any criminal offences.

The IPCC is still considering whether any disciplinary matters will be brought against the officers.

Armed police deployed

Mr Gaubert said he was on his way to meet friends when he suffered a fit on the bus and slipped into a coma which left him slumped on his seat clutching his rucksack.

Armed police were called to the bus depot in Headingley and when he failed to respond to their challenges he was shot with the Taser.

He said as this was happening, another officer was pointing a real gun at his head.

He was restrained and eventually came round in the police van.

He said it was only then that the officers realised it was a medical emergency, despite him wearing a medical tag round his neck to warn of his condition, and took him to hospital.

Mr Gaubert said he was told the police believed he looked "Egyptian".

He is completely traumatised by this - he is living with it every day

Solicitor Ifti Manzoor

Mr Gaubert's solicitor Ifti Manzoor said the incident had clear parallels with the shooting of Mr Menezes at Stockwell tube station and showed there was evidence of a breakdown in communication between the police on the ground and their commanders.

Mr Gaubert said: "When I heard about that Brazilian man in London I just thought, 'oh no, that could have been me'."

Mr Manzoor added: "The evidence is there was an order that officers be deployed and contain the scene. This direct order seems to have been ignored.

"I really appreciate that under the circumstances and at that time the police had an enormously difficult job.

"But Mr Gaubert was alone in a bus depot.

"He is completely traumatised by this. He is living with it every day."

'Potential security threat'

A statement from the IPCC said: "The IPCC managed an investigation into an incident on 13 July 2005 in which West Yorkshire Police discharged a Taser at a man while he sat on a bus in Leeds.

"The man was mistakenly treated as a potential security threat when he was, in fact, in a hypoglycaemic state. The investigation report was submitted to the Crown Prosecution Service (CPS) in November 2006.

"The CPS returned its initial decision in February 2007 stating that no officers should be charged with any criminal offences.

"Consideration was then given by the CPS as to whether any offences had been committed under health and safety law.

"A decision was received recently to advise that no charges would be brought under this legislation.

"The IPCC must determine whether any disciplinary matters need to be considered against the officers involved.

"Initial recommendations regarding discipline put forward by the police forces involved have not been agreed by the IPCC and discussions are ongoing. "

West Yorkshire Police said the matter was in the hands of the IPCC.