Activists want police to have more power to stop boycotts of Jewish and Israeli businesses, claiming that existing legislation is "deficient".

North-West Friends of Israel, which led a campaign to end the picket by pro-Palestinians of the Kedem Israeli cosmetics store in Manchester, has written to a group of MPs urging them to strengthen the Public Order Act.

The group's co-chair Anthony Dennison said police were forced to wait until Manchester city centre suffered serious disruption before temporarily curbing a boycott of the shop.

The at-times violent picket of Kedem led to neighbouring businesses losing tens of thousands of pounds of trade and bringing Manchester's equivalent of London's Oxford Street to a standstill.

"It's not just Kedem which suffers - it's Tesco, it's Marks and Spencer," said Mr Dennison.

"Peaceful protest can be intimidating, if demonstrators are stood outside a shop, holding placards with horrible images, are customers really going into that shop?"

He said that the Public Order Act should be amended to allow police to halt non-violent protests, if they disrupted "the lawful right of customers and shops to trade".