Marks & Spencer has warned the UK government that proposals set out by the European Union to ease the transit of goods to Northern Ireland risked increasing the administrative burden rather than reducing it.

In a letter to UK Brexit Minister David Frost seen by Reuters, M&S Chairman Archie Norman said the EU's proposals "sound reasonable, but could result in worsening friction and cost and a high level of ambiguity and scope for dispute."

Last month, the EU offered Britain a package of measures which stopped short of the overhaul that London is demanding.

The EU's executive said the measures could halve customs paperwork and cut checks on meat, dairy and other food products coming to Northern Ireland from mainland Britain by 80%.

In return for concessions, the EU wants proper sharing of live data, reinforced monitoring of supply chains and labelling to ensure British products do not slip into the EU single market via a Northern Ireland back door.

Archie Norman said the proposals could end up more costly to implement than full EU custom controls, with the relief offered in lighter touch border controls insufficient to offset the extra cost of labelling.

He said that labelling the circa 90 million products M&S sells annually in Northern Ireland would cost the retailer £9m a year.

Norman also noted that under the proposals a vet would need to oversee certification of 95% of product volume sent from the UK to Northern Ireland.

"This adds cost and a minimum of four hours per day into the supply chain which - with the other delays - means goods will take 1.8 days (45 hours) more to get to store than prior to the UK's departure from the European Union," he said.

He added that the product range available for consumers would be impacted.

Norman said the best solution is for Britain and the EU to agree a time-limited equivalence arrangement.

David Frost said yesterday Britain's preference is to strike a deal to improve post-Brexit trade arrangements for Northern Ireland and that the agreement can be reached by Christmas.

Marks & Spencer has struck a deal to sell some of its food products in Costa Coffee outlets, the companies said today.

They said that from spring next year over 30 M&S food products, including sandwiches and salads, will be available in over 2,500 Costa Coffee stores across the UK.

Costa, owned by Coca-Cola, is Britain's largest chain of coffee shops.

M&S said the move supported its strategy to make the retailer "more relevant, more often for families".

Last week, M&S beat forecasts for first-half profit and upgraded its earnings outlook for the second time this year, sending its stock soaring on bets that one of Britain's most elusive turnarounds could finally materialise.

Shares in M&S were up 2.1% this morning, extending 2021 gains to 71%.