THE chief executive of Wm Morrison hopes to keep the supermarket's prices the same across the British Isles, but added that there are too many unknowns to predict whether prices would rise or fall in Scotland in the wake of a "Yes" vote in next week's referendum.

The supermarket, which has a million and a half customers in Scotland, said the outcome of the vote was a matter for residents.

When asked whether independence would increase costs or prices for Morrisons, chief executive Dalton Philips said: "I could also say it would lower prices as well. It depends on what policies the Scottish government implements. Our job really has to be driving prices down.

"We believe in national pricing, we have it today, it's important in this market. There are too many variations, there are too many unknowns to predict what's going to happen to prices."

Morrisons, which has announced a 51 per cent slump in half-year profits to £239 million, said it opened fewer new stores than it had anticipated this year, though it aims to launch 100 a year from 2015, up from 60 to 70 in the current financial year.

The supermarket opened three of its new convenience stores in Scotland in the period, and expects to roll out the format further in the coming years. Mr Philips said the independence vote had not affected Morrisons' expansion plans north of the Border. "We are comfortable with the market, it's a great market; we just aren't going to be drawn on what it will mean for the economics of the business."

Turnover fell 4.9 per cent on the same period last year to £8.5 billion in the six months to August 3. Like-for-like sales slumped 7.4 per cent. The latest research from Kantar found that Morrisons' share of the grocery market slipped to 11 per cent over the summer, compared to 11.3 per cent a year ago, though its performance had shown signs of improvement in recent months.

In March, the supermarket pledged to cut the price of hundreds of products in response to growing price pressures from rivals including Aldi and Lidl.

"Everything we have seen since then has convinced us we made the right call at the right time," said Mr Philips, adding that Morrisons was adding more sales than the overall market in meat and produce.

Despite the slump in profits, Morrisons said it was raising its interim dividend five per cent to 4.03p per share, to be paid on November 10. Mr Philips said the supermarket "is getting back on the front foot".