The DUP and Sinn Féin have clashed over warnings that a no-deal Brexit could lead to electricity blackouts in Northern Ireland.
A single electricity market operates across the border on the island of Ireland.
British government officials have warned of risks of price increases and supply shortages, according to a BBC report.
Technical papers being drawn up by the UK include worst-case scenarios in the case of the country leaving the EU without a deal next March.
They do not necessarily represent the likely outcome.
Sinn Féin Stormont Assembly member Máirtín Ó Muilleoir said: "This is just the latest example of the catastrophic impact which the Brexit agenda risks imposing on the entire island of Ireland."
Mr Ó Muilleoir said costs could rise by as much as 34%.
"That is the kind of collateral damage that the Brexiteers in the Tory Party, aided and abetted by the DUP, are prepared to force upon the people of the North.
"It again reinforces the absolute necessity of ensuring the referendum vote in the North is respected by securing special status for us to remain."
However the DUP’s North Antrim MP, Ian Paisley, dismissed the warning.
He tweeted: "Fake news. Don't forget planes falling out of the sky, food shortage, mass unemployment and pestilence."
An all-island Single Electricity Market is designed to help keep down costs for consumers.
It is part of a UK-Ireland bilateral agreement rather than an EU one and has been in place for more than a decade.