From 30 April owners of the guns face a minimum of five years in jail if they do not get an appropriate certificate.

The crackdown is part of the government's plans to tackle gun crime.

Sussex Police have so far granted 42 firearms certificates to cover 97 of the weapons but it is thought there are many more of the guns in the county.

Safe place

Anyone who owns one of the self-contained air cartridge guns who does not want to obtain a certificate can hand their weapon into police before 30 April for disposal.

Otherwise they may face a jail sentence under the Criminal Justice Act.

Geoff Williams, Sussex Police assistant chief constable, said: "Sussex is still a safe place to live as far as gun crime is concerned.

"However, the force is not complacent and we fully support the government's new measures to tackle gun crime."

Home Office Minister Caroline Flint said: "Because this particular type of air weapon has been increasingly used in crime we have acted to ensure they cannot fall into the wrong hands.

"We do not want to criminalise legitimate sporting shooters, which is why existing owners may keep their guns if the police are satisfied that they are fit to be entrusted with such a weapon."