In an open letter ahead of this week's summit in Brussels, Eurelectric, which represents Europe’s electricity sector, urged negotiators to consider the impact on security of supply, energy bills and climate action that failure to reach a deal between the UK and the European Union would bring.
Recent UK government guidance highlighted a collapse in Brexit negotiations would jeopardise the single electricity market on the island of Ireland.
"In our view it would be hugely detrimental, from a cost and security perspective, to not preserve its function," Eurelectric secretary general Kristian Ruby wrote.
No deal would also create a "lose-lose situation" for the EU’s internal energy market and undermine its emissions trading scheme (ETS) after a recent surge in the carbon price.
"The overall balance of the EU-ETS could be severely disrupted by the withdrawal of UK, because the UK is currently the net supplier of allowances.
"We believe it will be of mutual benefit for a deal to be reached on the withdrawal agreement and it is vital that any political declaration includes energy and climate change as priority areas which are clearly addressed," the letter added.