Seventeen so-called 'ninja' swords were surrendered in Hertfordshire last month as part of a nationwide amnesty, police have confirmed.

The amnesty ran throughout July ahead of a change in the law, which came into force on 1 August, making it illegal to own such weapons in the UK.

The banned swords are defined as having blades between 14 and 24 inches long, with a straight cutting edge and a tanto-style angled tip. Even if kept at home, possession is now a criminal offence carrying a potential prison sentence of up to six months – rising to two years under new measures.

Chief Superintendent Nev Hanks, who oversaw the scheme, welcomed the response:

"It's great to get these kinds of weapons out of general circulation. Since the law change, owning one could result in a serious penalty. We're pleased people came forward to hand them in before the deadline."

Residents in Hitchin and across North Herts were able to surrender swords at designated police stations and, where applicable, claim compensation in line with government guidance.

The move forms part of a wider effort to halve knife crime nationally.