Union is dogged by bullying and harassment allegations as leadership battle-lines are drawn

The battle to succeed John Edmonds as the GMB leader starts today amid revelations that the union has spent up to £4m in recent years fending off allegations of sexual harassment and bullying against some of its most senior officials.

The election for the top job at one of the Labour Party's biggest affiliates – and a leading campaigner against bullying in the workplace – takes place as yet another of the union's top managers faces accusations of intimidation from a member of staff.

A source close to the union calculates that the GMB has spent £4m on 61 employment tribunal cases in the past six years. They involved allegations of unfair dismissal, bullying, sexual harassment and discrimination on the grounds of race, gender and disability.

The source said: "Proportionately, the GMB must have been the subject of more individual grievances than any organisation in the country. This union must rank among the worst employers in Britain."

Critics of the union's dictatorial approach to management also point out that the organisation is showing a £19m deficit in its pension fund for employees at a time when it is attacking retirement provisions in the private sector.

Several high-ranking officials have faced claims due to be heard at employment tribunals. Two months ago, Jerry Nelson, head of the union in Yorkshire and a prominent supporter of Paul Kenny, one of the two main contenders to take over from Mr Edmonds, was accused of bullying.

He was to face claims of harassment in an employment tribunal but it was settled before the hearing started. The union is understood to have paid £40,000 to the claimant, Amanda Phoenix, a recruitment officer. The total cost to the union of the case is thought to be £100,000, including lawyers' fees.

Ms Phoenix has signed a "gagging clause" routinely used by the union in such cases, which states she agrees not to make "unflattering or derogatory" comments about the GMB or any officers. If she does will forfeit the payment.

Mr Nelson is also to face allegations of bullying and harassment in a case due to be heard in the next few weeks.

Recently, Mr Nelson decided the union's official logo – depicting a man and woman hand in hand – was not "hard" enough and so the Yorkshire region now has a more masculine badge with eagles' wings spread on either side.

Another regional secretary facing employment tribunal cases is Robert Parker, head of the union in Scotland and another contender for Mr Edmonds' job. The 44-year-old former labourer is currently facing allegations of bullying and sexual harassment at an employment tribunal from Margaret McAvoy, his former personal assistant. Mary Senior, GMB Scotland's former equality officer, is accusing Mr Parker of victimisation and constructive dismissal after she agreed to testify on behalf of Ms McAvoy. The tribunal hearings concerning Ms Senior are due to resume today.

Mr Parker, who has been accused, during tribunal hearings, of attempting to intimidate witnesses, denies all allegations.

Gary Jones, the Lancashire regional secretary, also faces an employment tribunal today brought by Maxine Nixon, who claims sexual discrimination by Mr Jones since complaining on behalf of another of Mr Parker's alleged victims. Ken Gregory, the leader of the GMB in the West Midlands, left the union two years ago with a £100,000 severance deal after nine employees claimed he bullied them. Mr Gregory was exonerated by an internal union inquiry.

Six years ago, Nick Anderson, the union's northern region secretary, resigned after he was accused of high spending and financial irregularities.

The GMB general secretary has been accused of presiding over a "culture of bullying" in the organisation, both at the headquarters in south-west London and at big regional offices.

At one stage, employees at the union's HQ voted overwhelmingly to walk out after one employee was allegedly punched by a senior manager.

One of the main problems is thought to be the constitution of the union, which gives the regional secretaries virtually unfettered power and considerable scope for patronage.

Mr Kenny, regional secretary in London, said the present general secretary had failed to introduce a fair system for dealing with employees' complaints and called for an independent procedure. He said that not all the complaints made against senior officials were legitimate.

Mr Kenny pointed out he sanctioned the "anti-bullying" strike at union headquarters as leader of the part of the GMB representing staff at HQ. He argued that union officials with experience of recruiting and representing employees should not be elevated to jobs as regional secretaries without training in managing a large organisation. "We must be able to show that we will tackle bad and improper management practices as vigorously inside as outside the union," he said.

Kevin Curran, present leader in the northern region and the other leading contender, called for a review of the power of regional secretaries, saying there should be more "checks and balances". Candidates for such jobs should be made to "pre-qualify". He said he had already appointed an independent scrutiny committee in his region for dealing with complaints against senior management. He said it should be replicated at national level chaired by a legal professional.

A spokeswoman for the union said all the allegations against senior officials had been investigated by the union's internal complaints procedures and, in a "handful of cases", by employment tribunals. "All but a handful of cases have been settled or withdrawn without any negative finding against the union. We will always investigate thoroughly any allegations brought to our attention."

One senior GMB source said the union was in the middle of an election campaign and allegations would be "ten a penny". "It's like the final scene in Reservoir Dogs when everyone is pointing guns at everyone else and blasting away."

The GMB guidance on bullying

"Bullying can lead to stress-related illness, resulting in reduced job performance, absenteeism and a high staff turnover. Bullied individuals can suffer a number of symptoms including anxiety, tension, depression, lack of concentration and headaches. Examples of bullying can include verbal, written and/or visual intimidation, for example threats, shouting and swearing at the victim; insults to humiliate the bullied person in front of others or behind their back; physical intimidation, including assault; isolation and lack of support for difficult tasks, or excessive supervision; unfair allocation of work, changing work without consultation to include impossible deadlines or taking credit for the bullied person's work; refusing reasonable requests for training or blocking promotion. The GMB is aware that such behaviour does occur throughout the care sector and we are working to eliminate it. The GMB will give appropriate support to any member who feels that they are being bullied."