Possible Government moves to permanently relax Sunday trading laws for large stores would drive more of the region's small shops out of business, it is claimed.

A lobby of small shopkeepers has launched an angry protest following reports that big supermarkets have been in talks with the government about making permanent the longer opening hours that have been allowed during the Olympics and Paralympics period.

One small Norfolk retailer, who owns two grocery shops, said one of them had witnessed a disastrous 20pc drop in Sunday sales in the first three weeks large supermarkets had been allowed to extend their opening.

His concerns have been supported by the Rural Shops Alliance, which warns convenience stores nationally could lose as much as �480m a year if present legislation - which restricts stores over 3,000sq ft to 10am to 4pm Sunday opening - is lifted beyond the Olympics period.

The government's temporary opening hours amnesty was intended to create a feel-good factor for visitors during the games, but communities secretary Eric Pickles is reportedly open to a permanent change,

Nigel Dowdney, who owns the Stalham Shopper and Earlham Shopper in West Earlham, Norwich, said both shops had been affected but his Stalham High Street outlet had been worst hit.

He said: 'My Stalham shop is only 150m away from Tesco which has been opening until 10pm on Sundays.

'In the first three Sundays my shop lost 20pc of its sales and 30pc of its footfall - and that is in a period when we expect to see an increase in footfall and sales due to people coming here on holiday.

'We would also normally expect to see an increase in sales during a big sporting event with people buying their beer and crisps.'

He said Tesco had already had a major impact on Stalham and it was important to limit any further effect on the town.

'I employ 42 people across my two shops and, without any doubt, I would have to cut jobs if that loss in trade became permanent,' he said.

'I know there are businesses that rely on Sunday trading more than me and it would be a disaster for them.'

Ken Parsons, chief executive of the Rural Shops Alliance pressure group, said the impact on trade so far had been patchy but warned that was in part due to the fact that only a proportion of the region's supermarkets were currently taking advantage of the longer hours and customers had not yet become fully accustomed to them.

He said: 'A lot of rural shops are just about keeping going but without any buffer to protect them. Even a slight decline in sales will force some of them out of business.'

He warned that when villages lost their shop only about 7pc were successful in starting up a replacement community-run store.

Appealing to shoppers to vote with their feet, he said: 'Everyone is in favour of local shops in principle, but they don't realise they need to spend a bit more money in them to keep them going.'

A spokesman for the Keep Sunday Special campaign, a broad coalition of people concerned to protect the special character of Sunday, said they were very concerned about the rumours of possible further changes to the Sunday trading law.

She said: 'The government promised that this would not be a trial period for a future permanent change. So we now urge the government to refute the rumours or risk never being trusted again on this issue. As we have clearly seen in the past few years, while governments can do very little to build up the idea of a 'big society' they can all too easily destroy precious social capital, including small shopkeepers and community stores.'

The opportunity to open longer has been taken at Chapelfield Shopping Centre in Norwich where general manager Davina Tanner said: 'Ultimately we're living in a world that's fast moving and for people to have more choice when they can shop on Sunday is a very positive thing.'

An Asda spokesman said: 'Our customers like the convenience of us being open longer as it means they can shop when it suits them, not when it suits us.'

MP Brandon Lewis, whose Great Yarmouth constituency includes large urban supermarkets and small village shops, said: 'I spoke to some independent retailers before the Olympics who were relaxed about the temporary extension of Sunday opening hours for supermarkets but they would be concerned if it was made permanent.

'I have some sympathy for them because Sunday trading is their USP and I would be cautious about any permanent extension.'

The EDP approached Tesco for a comment but received no response before going to press.