Leaving the EU would threaten investment in energy, hitting jobs and pay in the industry, Labour has warned.
Shadow energy and climate change secretary Lisa Nandy spoke of the importance to energy firms of continuing to be part of the EU.
She told the annual conference of the GMB union in Bournemouth: “Over decades we’ve played a leading role in shaping an energy strategy for the EU that has given businesses the confidence to invest.
“A vote to leave is a leap into the unknown and this would threaten investment. The resulting loss of jobs and pay would be a tragedy.”