It was said that some may be given compensation if they handed in the ninja swords.
He added: “The ban on owning ninja swords was a very welcome change to the law which gives us a much better ability to limit the availability of these dangerous weapons.
“We have seen cases locally and nationally where these swords have been used to cause fear and injury, including the 2022 murder of 16-year-old Ronan Kanda, in Wolverhampton which prompted the national banning of these items.
“As a force, we of course support any measure which increases public safety and which can help us get dangerous weapons that can cause serious harm off our streets.”
Ninja swords are defined as having a blade between 14 and 24 inches, a straight cutting edge, and a tanto-style point.
Possession in private, supply, sale, and importation of ninja swords from this month onwards could lead to a prison sentence of up to six months, potentially increasing to two years under new measures.
Carrying a weapon in public already carries a penalty of up to four years in prison.
Ch Insp Kitchen added that police have reminded retailers of the changes in legislation and will continue to monitor stores across the country.
“Persons found in breach of legislation, either through selling these swords or now illegally owning them, face prosecution with a potential maximum sentence of two years in prison,” he said.
“Weapons such as ninja swords have no place in our communities and we intend to do all we can to enforce the ban now in place.”