A test operation by Nottinghamshire Police found nine Nottingham shops sold knives to people under the age of 18.
35 shops were visited during the operation, including those in the city and Netherfield areas between June and July.
Under the Criminal Justice Act 1988, it is a criminal offence to sell a knife to anyone under the age of 18.
The nine shops which failed the test will now be investigated and face prosecution, say Nottinghamshire Police.
Sergeant Heather Sutton, of Nottinghamshire Police’s Knife Crime Team, said: “We know knives can be easy to come by and this operation is a small aspect of our multi-faceted approach to combating knife crime.
“We are pleased to see the steps the shops within Nottingham have taken to prevent knives getting into the hands of children, and will work with those who failed the operation to prevent them from making illegal sales again.
“Our proactive and preventative activity around knife crime will continue.”
Notts Police have been running this operation for three years, an operation which involves making use of young people under the age of 18, to act as a customer in order to attempt the purchase of a knife.
The rate of failure when attempting the purchase has seen a 25 per cent improvement, compared to the 45 and 44 per cent fail rate in the last two years.
Notts Police urge anyone to report any information about knife crime to 101, or you can report anonymously to Crimestoppers on 0800 555 111.
