Privatisation examples include private firms running GP services

It is the first national strike in the NHS for 18 years. Union officials say it will cause "major inconvenience" and could see operations cancelled.

The row is over the sell-off of the supply network to German firm DHL.

The government says it has detailed plans in place to keep disruption during any strike to a minimum.

The Unison union has yet to announce when the strike days will be, but the action could last up to three days.

Eight hundred staff were balloted and 74% voted yes to strike, on a 66% turnout.

Hospitals will get seven days notice of the strike but they have to order equipment three days ahead and have limited space to store stockpiles.

'Not hardliners'

The service supplies 48,000 lines of products, including bedpans, latex gloves, syringes, bandages and Weetabix.

More than �22bn of orders over 10 years will be affected. DHL says it will save the NHS �1bn in that period but insists quality will not be sacrificed to cut costs.

The move is the biggest example of what some regard as "creeping" NHS privatisation.

Announcing the strike, Mr Prentis told the TUC conference: "These are not troublemakers, not hardliners but workers who care deeply about the NHS, who want to stay part of it, who want to play their part in saving it.

"Hardworking public service workers who have never taken action before."

'No quality cuts'

The last time there was a national strike in the NHS was 1988, when midwives took action.

From 1 October, DHL - best known for delivering parcels - will supply everything from stationery to bed linen and MRI scanners.

A deal reached earlier this month will see 1,700 employees from parts of NHS Logistics and the NHS Purchasing and Supply Agency transferred to the private sector.

The Department of Health said most hospitals had their own supply and delivery arrangements and most products used by the NHS would not be affected by the strike.

A spokesman said: "All distribution centre controllers have been instructed to maintain a full staff complement at all times and to keep in place the temporary staff recruited for holiday cover so that we can respond to customer demand."

He said private sector involvement in the NHS was nothing new - for example, pharmacists were paid for the services they provided and hospitals had always bought services from private firms.

"The existing NHS Logistics operation uses trucks and drivers from TNT rather than directly employed NHS staff," added the spokesman.

'Unprecedented anger'

The news comes as the unions launched a joint campaign to "defend the NHS".

At a fringe meeting an alliance of unions vowed to make the government rethink its NHS reform plans through a series of demonstrations.

The NHS Together campaign combines TUC affiliated unions with groups like the British Medical Association, Royal College of Midwives and Royal College of Nurses.

TUC general secretary Brendan Barber said it was an "unprecedented alliance" which reflected the "unprecedented anger about the pace and direction of change" in the NHS.

Mr Barber said he had met Health Secretary Patricia Hewitt to try to make her recognise the anger among NHS staff.

"I think we have still got a long way to go to get the government to realise there needs to be a change in direction," he said.

Lobbying Parliament

He criticised ministers for failing to consult about the reforms and warned they could face a backlash from voters.

"The government would under estimate at their peril quite how precious to the British people is the NHS," he said.

The campaign will organise regional demonstrations which union leaders say could involve 10,000 people.

There will also be a lobby of Parliament later this autumn and a national demonstration next spring.

But the government says it is not turning the NHS into a private service and will keep the principle that care should be free at the point of need.

Private firms will be used if they can give better value for money and better treatment, say ministers.