Morrisons today (21 January) warned that trading would be "tough" in 2010 despite UK consumers splashing out over Christmas.

The UK's fourth-largest grocer this morning booked a 6.5% rise in like-for-like sales in the six weeks to 3 January, faster sales growth than that achieved by rivals Tesco and Sainsbury's.

The UK's largest grocers have cited rising Champagne sales or strong demand for premium, own-label ranges as evidence of healthy demand over Christmas.

However, concern over the prospects of the UK economy, including the inevitability that taxes will rise to pay down public debt, has led some industry watchers to dispel the notion that the festive period is an indicator of certain growth in 2010.

Morrisons finance director Richard Pennycook said the retailer had seen its party food sales jump 90% and its Champagne sales double but he was less than upbeat about the outlook for the UK economy this year.

"We certainly saw that customers did enjoy their Christmas; people save for it and we saw our premium ranges have good growth," Pennycook said on a conference call with reporters.

"But I don't think that's a sign that there will be a real change in behaviour in 2010. We see 2010 being tough in the same way that the back half of 2008 and the whole of 2009 was."

Justin Scarborough, an analyst at RBS, said Christmas 2009 was the fourth festive period in a row that Morrisons had outperformed the market.

"Cumulatively over the past four years, Morrisons has increased its sales by nearly 40% over Christmas, which is unprecedented and shows, in our view, just how well the group's strategy is clearly working," Scarborough wrote in a note to clients.

Pennycook said Morrisons had attracted a record number of shoppers over Christmas and had lured consumers from its rivals.

"Our growth was broad-based and we won customers from all our competitors," Pennycook said.

The Morrisons finance director is reportedly in the running to succeed Marc Bolland, who was poached as chief executive by Marks and Spencer in November.

Industry commentators have expressed concern that Morrisons needs to swiftly name a new chief executive to ensure its strong recent performance continues.

Chairman Sir Ian Gibson refused to be drawn on when Morrisons would name a new chief executive or who was on the shortlist for the top job.

Sir Ian said only that an announcement was not a "long way away". He also refused to comment on Morrisons' talks with Bolland over when the Dutchman could officially join M&S.

Shares in Morrisons were down 1.7% at 293.7p at 11:27 GMT this morning.