Former executives at France Télécom have been given prison sentences and fines after being found guilty of “institutional harassment” and creating a culture of routine workplace bullying that sparked a number of suicides at the company.

The landmark ruling is likely to send shockwaves through the French business world. It is the first time managers have been held criminally responsible for implementing a general strategy of bullying even if they had not dealt directly with the staff involved.

The former state-owned firm, which has since been rebrandedas Orange, was given the maximum fine of €75,000 (£64,000).

The ex-chief executive Didier Lombard, his former deputy Louis-Pierre Wenes and the human resources director Olivier Barberot were each given a one-year sentence, with eight months suspended, and fined €15,000. They were found guilty for offences that took place in 2007 and 2008 when cost-cutting plans were put in place. Lombard’s lawyer said he would appeal.

The court heard harrowing accounts of what one employee had called a terrifying management strategy to destabilise workers. Families described systematic psychological abuse against staff as bosses focused ruthlessly on cost-cutting and job cuts.

Between 2008 and 2009, 35 employees killed themselves. The company had been privatised and was undertaking a restructuring plan during which bosses set out to cut more than a fifth of the workforce – more than 22,000 jobs.

The investigation focused on the cases of 39 employees, 19 of whom killed themselves, 12 who attempted to, and eight who suffered from acute depression or were signed off sick as a result of the pressure.

Facebook Twitter Pinterest The former France Télécom CEO Didier Lombard (centre) arrives at the Paris courthouse on Friday. Photograph: Lionel Bonaventure/AFP via Getty Images

Many of the workers, including one who jumped out of a fifth-floor window in front of her colleagues, left notes expressing deep unhappiness at work or saying the company had made their lives unbearable.

In July 2009, a 51-year-old technician from Marseille killed himself, leaving a letter accusing bosses of “management by terror”.

Noémie Louvradoux had told the court how her father, Rémy Louvradoux, a 57-year-old public sector worker at France Télécom, killed himself days before her 18th birthday.

She said: “France Télécom had destroyed his life and left him no way out.”

Louvradoux’s case was said by lawyers to sum up the toxic working environment. He had worked his way up in the company from a low position to a more senior local role, but in 2006 his job was scrapped and he was made to relocate and change jobs four times in three years, while trying to work as hard as possible to avoid further change. He had written to company bosses in 2009 complaining of an endemic problem, saying: “Nothing is being done to face it up to it: suicide remains the only solution.”

Lombard, the CEO, told the court he never received the letter, which was most likely to have ended up with the human resources department.

Another worker, Daniel Doublet, described how management stopped giving him work to do. He lived in the Paris area but was relocated to Besançon, 280 miles (450km) from his family, and his tasks were never defined. “Imagine the isolation I felt,” he said. “It was as if I was nothing … a parasite.”

The widow of Michel Bugead, another worker who killed himself, said he had written by email to management to express concerns. She said he, like many others, “was very attached to the company which had allowed him to rise up the ladder in society”.

Lombard denied management bore any responsibility for the deaths. He denied saying in 2006 that he would “get people to leave one way or another, either through the window or the door”.

He told the court: “The transformations a business has to go through aren’t pleasant, that’s just the way it is, there’s nothing I could have done.”

Lombard, who was forced to step down in 2010, a few months after the suicides became headline news, argued that he was battling to save France Télécom from bankruptcy after its privatisation in 2004.

• In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at www.befrienders.org.