Union leaders are seeking urgent talks with power giant National Grid after an email sent by mistake raised fears of 400 job losses.
The GMB said the message made it clear the company was drawing up plans to cut jobs at its sites in Northampton and Hinckley.
A company spokesman said: “National Grid has the goal to be the most effective and efficient of Britain’s local gas distribution networks.
“To help achieve this, National Grid has been looking at a number of different options for the future structure of its customers operations team based at Northampton and Hinckley.
“We are still developing final proposals and plan to present them to staff and their representatives shortly for consultation. Unfortunately, an unfinished draft document was emailed inadvertently to a number of employees.
“It would not be appropriate for us to comment on the contents of this working draft, save to say that no decisions have been made by National Grid about our final proposals.
“We are committed to meaningful consultation with our staff and their representatives.”
GMB official Gary Smith said: “We don’t believe there can be meaningful consultation. We know National Grid have already expressed a preference for the option they intend to pursue.
“We have a Government claiming the private sector will create thousands of new jobs as they decimate the public sector, and we have a Government regulator, Ofgem, driving companies to slash jobs.
“These job cuts will come at a time when the gas infrastructure is creaking with the number of gas escapes. We have had record numbers of gas leaks and we have a real worry about the impact of these cuts.”