Paramedics and ambulance workers are refusing to treat patients with a history of violence unless police can provide an escort.

Figures from Avon Ambulance Trust show nearly half of its 245 staff have experienced violence or aggression from patients over the last 12 months.

The new scheme involves compiling a register of people who have been violent in the past.

Staff have said that unless there is a major medical emergency, anyone on the register will not be treated without a police escort.

Darren Eden says violence is a growing problem

The ambulance trust is the first in England to act on the government's 'zero tolerance' policy, introduced in October 1999 to tackle violence towards health service staff.

Avon Ambulance risk manager Darren Eden says that violence towards staff is an increasing problem.

While admitting that it may lead to delays in treatment in certain cases, Mr Eden denied that lives would be put in danger.

"If it's a life or death situation then our staff are able to override the precautions, if someone is having a heart attack then they're not going to be a danger to staff," he said.

Mr Eden said the decision to place someone on the register would be taken by a panel of senior NHS managers at the trust, with the patient being informed and also given a chance to appeal.

The move has been welcomed by health service unions, who have called for similar schemes to be introduced across England.

A spokeswoman for Avon and Somerset Police said they were supporting the scheme.