Plans to ban daylight saving in Scotland are in breach of European Union laws and should be scrapped, a new report has warned.
Brussels is planning to end the practice of changing the clocks twice a year after research found it was unpopular.
It would mean EU countries had to choose to adopt permanent summer or winter time, meaning the UK would need to stick to a permanent European timezone to bring it into line with the Continent.
The initiative has always faced sharp criticism from Scotland.
For years, farmers north of the border were staunchly opposed to a forward shift in the clocks on the grounds those working in the far north of the country would disproportionately suffer during the long, dark mornings.
Although the changes are not due to come in until after the UK leaves on March 29 next year, the UK would have to adopt the measures during any transition period, peers said.
Current rules mean every state has to switch to summer time on the last Sunday of March and switch back to winter time on the last Sunday of October but the European Commission proposals would stop the practice.
EU countries fall into three timezones - Greenwich Mean Time, Central European Time and Eastern European Time.
The move would “not affect the choice of time zone” and it would “ultimately remain each member state’s decision whether to go for permanent summer or wintertime (or a different time)”, the proposals state.
European Commission President Jean-Claude Juncker has said millions “believe that in future, summer time should be year-round, and that’s what will happen”.
The move needs the support of all EU countries and backing from MEPs to become law.
In its report, peers on the EU Internal Market sub-committee, recommended the House of Lords issued a “reasoned opinion”, a mechanism that allows parliaments to register concerns about proposals.
They said the decision to end daylight saving clock changes should not be made by the EU.
The recommendation will be debated on Wednesday.
Committee chairman Lord Whitty said: “The European Commission’s proposal to end seasonal time changes goes beyond its remit and is not in compliance with the principle of subsidiarity.
“We are therefore recommending that the House of Lords issues a reasoned opinion.”