Bosses of the UK's largest supermarkets have warned "urgent intervention" is needed by the Government to prevent "significant disruption" to Northern Ireland's food supplies, due to post-Brexit border arrangements.

In a letter to Michael Gove, Cabinet Office Secretary, the chief executives of Asda, Tesco, Sainsbury's, Iceland, Co-op and Marks & Spencer said it is "essential" to find a long term solution with the EU before March 31, on sending food to Northern Ireland. It was also signed by Helen Dickinson, chief executive of British Retail Consortium.

Since December 31, Northern Ireland has remained as the only part of the UK in the EU's single market for goods, meaning foods entering from Great Britain have to be professionally certified and are subject to new checks.

The end of March marks the end of a Brexit grace period, which has exempted some retailers such red tape in their supply chains.

Current proposals for border arrangements - including new bureaucracy and need for certification - are "unworkable" in the short timescale, the group said.

Without intervention, they argued, supplies and affordability of food in Northern Ireland will worsen.

Already, many grocers in the region have had difficulty stocking shelves over the new border regime. M&S has temporarily withdrawn some food products, warning supplies are under threat.

In the letter, the supermarkets urged the Government to "work with us to ensure the long term sustainability of the Northern Irish grocery market", calling for more time to be agreed with the EU to sort out a system.

"We accept clear progress needs to be made by April 1 and are happy to discuss out issues and solutions directly with EU officials," they said.

The grocers also proposed a dedicated Cabinet Office group, with members including supermarkets' own experts, to work out a solution for customs and food controls.

A government spokesman - reported by the BBC - said: "The grace period for supermarkets and their suppliers is working well, goods continue to flow effectively between Great Britain and Northern Ireland and we are working intensively with industry as new requirements come in."