The selling giant Ebay hopes that people power will help stamp out the “underhand” tactics of manufacturers seeking to control how their goods are sold online.

It has emailed a petition to millions of sellers who use its site, asking them to sign it to help bring about a change in EU law so manufacturers can be prevented from blocking internet sales of their branded goods.

According to eBay, half of 900 small online sellers in the UK and other parts of Europe — many of whom operate shops on eBay — said they had been bullied by suppliers over online sales.

A third faced complicated conditions and many more faced unexpected supply problems.

European law governing internet sales is due to be revised this year.

Ebay hopes it can lobby for a change in the law so that it will be illegal for brands to impose blanket bans on internet sales and illegal to block the resale of items.

It also wants to prevent manufacturers from insisting that small internet retailers have a bricks-and-mortar store before selling online.

Mark Lewis, managing director of eBay UK, said: “By blocking online sales, these manufacturers are denying consumers access to the widest possible selection of goods at the lowest possible prices.

“Consumers already value the convenience of the internet. And with the recession biting, consumers deserve a fair deal. That is why we are calling on lawmakers to break the grip that manufacturers have over internet sales.

“Brands must not be able to get away with this kind of threatening behaviour, and we are calling on shoppers and retailers right across Europe to speak out against it.”

John Pemberton, an online retailer specialising in clothes, said: “Only recently I was threatened by a big high street name for selling goods which I bought from a legitimate wholesaler.

“Small businesses like mine are no match for the huge resources of big brands, so it is hard to put up a fight.”