The Electoral Commission has been urged to stop allowing supermarkets to set up in-store polling stations on the grounds it undermines small retailers.

Tory backbencher, Sir Nicholas Winterton made the plea this week during a House of Commons debate about possible changes to the rules for siting polling stations.

It has been six years since a Tesco in Cardiff became the first supermarket to be used in this way, during the 2001 general election.

Since then there have been repeated calls to make greater use of supermarket sites as a way of encouraging more people to vote.

However Macclesfield MP Sir Nicholas said he saw dangers in mixing shopping baskets with ballot boxes. "It would be most undesirable if any polling station or ballot box were placed in superstores such as Tesco," he said. "Tesco has a big enough advantage without people being advised to go into those stores, which undermines the small retail sector."