EDF, which is 85 percent state-owned, aims to shed 5,200-7,000 jobs by the end of its four-year restructuring plan.
At the end of 2019 it hopes to have 60,200-62,050 employees, compared to 67,200 at the end of 2015, according to several trade union sources.
The unions are worried about this downsizing, given that the company has embarked on major projects including the construction of two nuclear reactors at Hinkley Point in the UK and the overhaul of France's nuclear power stations.
The unions want to know if the figures take account of the proposed closure of France's oldest operating nuclear reactor at Fessenheim in Alsace.
In 2016 more than 2.000 jobs were cut, according to the Force Ouvrière union.
The initial plan projected savings of 700 million euros over three years.
That figure has been raised to one billion euros by 2019, while the government wil contribute three billion euros the company, which is heavily in debt.
"How we can produce more energy, propose more research and development while cutting jobs?" Philippe Martinez, the leader of the powerful CGT union, asked on iTélé TV on Thursday morning, claiming that EDF's employees are paying the price of a "bad business strategy".