Possible strike action by front-line ambulance staff over working conditions moved a step closer today after a union announced a formal ballot on industrial action.

The dispute with the East of England Ambulance Service Trust (EEAST) centres on the number of shifts that over-run, and concerns staff regularly have shorter meal breaks than they are entitled to.

The trust said it was disappointed by news of the ballot, and urged Unison to agree to seek mediation.

The news follows an indicative ballot in March, which Unison said 60pc of its 'patient-facing members in A&E operations' joined, with 90pc saying they would vote for industrial action over late finishes. That was followed by six weeks of negotiations.

Unison branch secretary Fraer Stevenson said: 'It's heart breaking to see front line staff working under such pressure and for the trust's board to be given repeated evidence of this – but fail to act. We have little choice now after over a year of many meetings and no meaningful action, than to consider industrial action.'

In a statement, the EEAST said: 'The trust is committed to working with Unison to develop sound and sustainable working practices to ensure staff welfare whilst maintaining excellent patient safety.

'Both sides have been working incredibly hard to tackle this issue for the benefit of staff and patients.

'Whilst we are disappointed Unison has taken the decision to ballot staff, we would urge Unison to take up our offer of approaching ACAS to facilitate a mediated and final joint resolution.'

Figures from EEAST show 2,995 shifts finished more than an hour later than planned in December. The figure rose to 3,639 in January 2016.

North Norfolk MP Norman Lamb said he 'very much' shared the concerns of staff, and called for the EEAST and Unison to 'get around the table to find a solution'.

He added: 'My plea is that everything is done to find a reasonable way forward which avoid any risk of strike action.'

Do you have a health story? Email nicholas.carding@archant.co.uk