Formal notice of a strike by health workers has been issued ahead of a crucial meeting aimed at averting the planned walkout.

The GMB union said it had served NHS employers in England and Northern Ireland with the necessary information about the stoppage on January 29 involving hospital and ambulance workers.

Ambulance members of the union will strike for 24 hours from one minute past midnight, while other health workers will take action for 12 hours from midday.

Members of Unison and Unite are also set to go on strike on the same day in a long-running dispute over the government's refusal to accept a pay review body's recommendation of a one per cent rise for all NHS workers.

Health Secretary Jeremy Hunt chaired a meeting of the Government's emergency Cobra committee to discuss contingency plans for the strike.

A Department of Health spokesman said: 'We want to see the unions call off the industrial action planned at a time when services are under significant pressure, given that only 13 per cent of their members voted to strike.

"We are doing everything possible to ensure vulnerable patients are not put at risk, and the Health Secretary chaired a Cobra meeting this morning on contingency plans, with a particular emphasis on patient safety."

Two rounds of talks between unions and the Health Department have been held this week, with another meeting due today in a bid to head off next week's strikes.

Rehana Azam, national officer of the GMB union, said: "It has taken months to get the talks started in the NHS pay dispute.

"We are all well aware of the pressures on NHS staff who have worked tremendously hard despite the government taking an axe to their independent pay review body recommendations.

"Should a tangible offer emerge as a result of these current talks GMB will take that offer back to members. We are not in a position to call the strike off until we have such an offer. Notices have been served to the relevant NHS employers today."