Hundreds of ambulance workers are to be consulted on future industrial action.

The Sussex Ambulance Service branch of Unison is joining forces with colleagues in Kent and Surrey to ask members' views.

The three services could be merged to create a single ambulance trust in the next year as part of a shake-up of the NHS throughout the South-East and England and Wales.

The changes are mainly administrative and are not expected to affect front-line patient care.

The consultation has been called because of the continuing row about the way negotiations have been handled for a new pay and conditions deal under the Agenda for Change NHS scheme.

Concerns have included alleged interference by managers over what level of pay should be given to paramedics and ambulance technicians and planned changes to meal breaks and rest times.

Proposals have included replacing paid meal breaks with unpaid ones and cutting rest times from two 30-minute breaks per 12-hour shift to a single 20-minute one to compensate for loss of income.

Staff say this is not enough time for people to relax and refuel and could affect their performance when dealing with patients.

In a message to Unison members, the Sussex branch executive said consultation letters would be sent out in the next week.

They said: "We hope members will agree these measures are a step in the right direction to ensure Unison supports its ambulance worker members in these crucial issues."

The ballot asks members to indicate whether they would be prepared to undertake industrial action should employers fail to implement the Agenda for Change under the terms of the original agreement.

They are also asked whether they would agree to the union withdrawing its cooperation with the ongoing review of possible ambulance service mergers if the Agenda for Change issue is not sorted out.

A Sussex Ambulance spokeswoman said most staff had been assimilated into the new pay scheme.

She said: "However, we recognise there are still some issues up for discussion at a national level."

Unison has about 670 members in the Sussex ambulance service.

Previous industrial action in Sussex involved refusing to do overtime and stopping filling out record sheets.