A hard Brexit that would see Britain no longer trade energy in the Internal Energy Market is likely to increase British energy bills, the House of Lords' EU Energy and Environment Sub-Committee is expected to say on Monday.
Britain could also face energy supply shortages, while the lack of access to EU labour is a threat to the construction of a new generation of civil nuclear sites.
Liberal Democrat Brexit spokesperson Tom Brake said:
"This report shows how leaving the Single Market and the Internal Energy Market is going to hit people's wallets, with bills rising heavily at a time when inflation has already made it harder to make ends meet. Already the weekly shop has become a major financial concern, with soaring prices of fish and vegetables resulting in food inflation of 4.2% in the run up to Christmas.
"The committee is also right to highlight the problem of access to EU labour for major construction projects. As the recent collapse of Carillion demonstrates, the construction industry is already badly hurting and the Conservatives' foolish and unnecessary efforts to leave the Single Market is only going to damage the sector further."
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