Unions have warned patients in rural areas could be at risk if ambulance staff take industrial action.

Paramedics will not operate standby ambulances in areas cut off from ambulance stations.

The move, which unions admit will affect response times, comes after members voted in favour of industrial action last week.

The action will also see a ban on voluntary overtime and a refusal by employees to log response times.

About 600 members of Unison, the Association of Professional Ambulance Personal and Amicus-AEEU are calling for a five per cent pay rise and better working conditions.

Unless a resolution can be found, industrial action will begin from 7am on Wednesday, February 12.

Standby ambulances wait in areas further away from ambulance stations to ensure they can reach casualties within specified response times.

The Government wants crews to reach 75 per cent of life-threatening emergencies within eight minutes.

Between April and December 2002, crews in Sussex missed the target by two per cent.

Sussex Ambulance Service NHS Trust has awarded workers a 3.6 per cent pay rise. The average ambulance worker earns £20,000 a year.

Unions also want a decrease in the working week, from 42 hours to 40 and an increase in leave.

In addition, they are calling for cost-of-living supplements, similar to those awarded to nurses and the option for early retirement at 55.

The trust has offered some employees a three per cent rise in exchange for an extra day's leave.

Trust personnel director John Kirby said: "We are willing to sit down with the unions and listen to their point of view but we feel it unlikely we will be able to afford to pay them any more."