Trade union officers at the Transport Salaried Staffs Association (TSSA) are set to strike on Wednesday in protest at a “badly handled” staff restructuring.

Union organisers and support staff, who are members of general union GMB, said they were concerned by a “refusal” to guarantee protection for all staff members in the re-structuring process.

A GMB newsletter shown to the Morning Star says members are also worried by proposals to “put over 30 staff through an assessment process for generic organiser and support roles.”

The news follows extensive negotiations between the union’s leadership and the GMB, which reps said led to a number of additional concerns being resolved.

Negotiations have now been ongoing for 11 months, and follow a series of unsuccessful merger talks between TSSA and other unions.

The union’s management and staff unions have agreed there will be no compulsory redundancies, but GMB reps fear assessments could result in staff being placed on six-month “development plans.”

A source close to GMB members at the union told the Star: “Staff may be told they’re not suitable for any job, and development plans can break people’s spirits.

“We’ve put a number of positions to management to avoid this, but they’ve all been rejected out of hand — because they’ve included protecting all staff and not having assessments.”

Union staff will form a picket line from 7am on Wednesday morning outside TSSA’s north London headquarters.

Mr Cortes said he hoped the situation could still be resolved.

It is understood management has suggested new conciliation talks at Acas.

Tssa is Britain’s second-largest rail union, representing booking office clerks and ticket inspectors among others.