Morrisons is to open for an extra hour on the crucial last Sunday before Christmas as it looks to take full advantage of its busiest day of the year.

The grocer will open from 9am rather than 10am and close at 4pm for shoppers to browse for an extra hour if chief executive Dalton Philips and Asda boss Andy Clarke’s forceful attack on Sunday trading laws does not come to fruition.

Philips and Clarke have written to business minister Michael Fallon to demand Sunday trading laws are relaxed on Sunday December 23 which would allow Morrisons to trade for the “two to three” extra hours.

Philips is due to meet with Fallon tomorrow. Asda and Morrisons have been joined by Marks & Spencer’s and Selfridges in lobbying Government to relax laws on large retailers trading on Sunday.

Philips said: “David Cameron talks about an economic war. Things like this are an easy way to help the economy. We cannot be puritanical about this.

“If you can relax it for the Olympics why can they not on the 23rd. It’s so stressful for families at Christmas.”

Asked whether Sainsbury’s chief executive Justin King and Tesco boss Philip Clarke had written to Fallon, Philips said: “Different retailers have different views. If you have a large convenience business you might think slightly differently about it.”