Boxing Day is traditionally one of the biggest shopping days in Britain's retail calendar as store groups kick off post-Christmas sale events.

However, trading this year could be more subdued, given the government's announcement on Tuesday that it would temporarily relax COVID-19 restrictions - allowing up to three households to meet at home over the Dec. 23 to Dec. 27 period.

M&S said it will now close all of its owned stores in the United Kingdom, as well as its customer service and distribution centres in Castle Donington, central England, so that as many employees as possible can spend time with family and friends on Christmas Day and Dec. 26.

"This is a big decision, but it is absolutely the right one given the incredible effort everyone has made in the most challenging of circumstances," said Chief Executive Steve Rowe.

Shares in the group were down 3.1% at 1425 GMT, extending 2020 losses to 39%.

In August, M&S cut 7,000 jobs and earlier this month reported the first loss in its 94 years as a publicly-listed company after clothing sales were hammered by the COVID-19 pandemic.

To try and make up for some of the trade lost during the various lockdowns across Britain, M&S plans to operate its longest ever trading hours this Christmas, with around 400 stores open until midnight from Dec. 21 to 23 to help manage capacity while adhering to social distancing requirements.

M&S, along with the wider retail sector, is also lobbying the government to relax strict Sunday trading restrictions in December.

(Reporting by James Davey, Editing by Paul Sandle and Emelia Sithole-Matarise)