Police have revoked 20 gun licences in the past year, after their owners were deemed a danger to the public, the Mercury can reveal.

Leicestershire Constabulary withdrew the certificates after individuals were convicted, cautioned, fined or arrested for offences, including threats to kill, harassment and assault.

In the 12 months up to June, one gun licence was revoked after the holder threatened self-harm.

The Mercury asked police for the figures under the Freedom of Information Act after Derrick Bird killed 12 people with a legally-owned rifle and shotgun in Cumbria, in June.

He turned the gun on himself after the killings.

Home Secretary Theresa May promised that once the police investigation was complete, there would be a review of gun laws.

Figures show there are more than 11,000 shotgun certificates and more than 2,100 firearms licences held by people in Leicestershire and Rutland.

Many are held by farmers, who may keep guns for pest control, or by people involved in hunts and shooting sports.

Rural lobbying group the Countryside Alliance is in favour of a debate on gun legislation, but warns that it could be impossible for any law to prevent another massacre like the one in Cumbria.

A spokesman said: "It's important to remember that we do have strict legislation in the UK already and the Countryside Alliance doesn't think that's a bad thing.

"It's in our interests to ensure the law is as good as it can be, but if a switch is going to flip in someone's head, there might be nothing that we can ever do to prevent that."

Handguns were banned following the Dunblane massacre in 1996, when Thomas Hamilton opened fire at a school, killing 16 children and their teacher.

Michael Ryan's massacre of 16 people in Hungerford nine years earlier led to the banning of all modern semi-automatic, rapid-fire rifles.

As in Cumbria, legally-held weapons were used in both incidents.

The Gun Control Network is lobbying for changes to gun laws in the UK, including preventing gun owners from keeping ammunition in their homes and a single certification system for all gun owners which includes airguns as well as rifles and shotguns.

Gun certificates are valid for five years and cost £50.

Inspector Pete Wells, firearms and explosives licensing manager for Leicestershire Constabulary, said: "Each application follows a series of thorough checks including disclosing previous addresses and convictions and the applicant must show a good reason to possess a firearm."

Figures show the number of shotgun licences has fallen by more than 300 since 2005, when the Hunting Act was introduced, making it illegal to hunt foxes with dogs.

The number of firearms certificates has risen by about the same number since then.

Police figures also show there were 22 arrests of people found illegally possessing guns in 2009-10 in Leicestershire, compared with 30 the year before.

Nationally, firearms were used in 14,250 recorded crimes in 2008-09, an 18 per cent fall on 2007-08, and the fifth consecutive annual fall.