Royal Mail managers are to increase the level of industrial action being taken over a long-running pay dispute.Workers voted to take action when Royal Mail refused to improve on a management pay rise of 1.3%, and the 4,800 managers involved began a 'work-to-rule' motion on 4 May.

This is to be ramped up to an overtime ban as of 18 May, following unsuccessful talks earlier this week.

Unite said that strike action is a possibility if a resolution is not reached soon.

The union’s officer for Royal Mail managers, Brian Scott, said: “We had talks on Tuesday (10 May) with the Royal Mail management, but no progress was made – they appear to have dug their heels in over making an improved pay offer.

“Unite is willing to sit down with the company to find a solution, but it needs to acknowledge and recognise the valuable contribution that Unite members make to the success of the business, which the current pay offer does not reflect.”

A spokeswoman for Royal Mail said: “Royal Mail is disappointed that Unite is instructing managers to not carry out overtime work and to work to rule over junior and middle managers' pay.

“Royal Mail also has 3,000 senior managers working as normal in the business as well as 1,900 managers who are not Unite members.”

The spokeswoman added that the company had “robust contingency plans in place” to prevent service disruption.

She added: “Our mail centres, delivery and collection operations will operate as normal given that our 120,000 postmen and women will be working in their daily jobs. We continue to discuss this matter with Unite.”