Germany has some of the strictest firearms laws in Europe, although there are four illegal guns on the streets for every properly registered weapon.

According to data from the German Firearms Register, there are almost 5.5 million guns in private ownership belonging to 1.4 million people.

But research by the Frankfurter Allgemeine Zeitung in January estimated there are up to 20 million illegal firearms in Germany.

Killer Ali David Sonboly used a Glock 17 semi-automatic pistol, file photograph, to kill nine people in Munich

Ali Sonboly, pictured, had 300 rounds of ammunition for his Glock 17 semi-automatic handgun in his backpack

Sonboly shot himself in the head after murdering nine people during his rampage in Munich yesterday

There are serious restrictions on the types of guns made available to the general public. Military-style weapons, those which are capable of automatic fire and certain high-powered weapons are banned.

To own a gun in Germany, the individual has to obtain a licence. The prospective owner has to be at least 18 and show they have a reason for owning the firearm.

Anyone with a mental illness, or those with a drug or alcohol dependency will likely be refused a licence.

Applicants under 25 have to undergo a psychiatric test.

Prior to the 1928 Firearms and Ammunition Act, there were very few restrictions to gun ownership.

However, Hitler dramatically restricted gun ownership to prevent opponents of Nazism from accessing firearms.

He liberalised the rules in 1938 to exempt Nazi party members from the restrictions in preparation for the war.

Following the Second World War, the German government passed federal laws in 1972 to restrict gun ownership.

New rules were brought in following a school shooting in the city of Erfurt, where 16 people died.

A school shooting in 2006 saw and 18-year-old enter his former school and shoot five people before killing himself. This shooting saw restrictions on the distribution of violent computer games to young people.

In 2009, officials further tightened gun laws after Tim Kretschmerat, 17, shot dead 15 people at a school in Winnenden.

The new rules gave authorities the right to check on where guns are stored when not in use.

Authorities also have the right to make spot checks.

In 2015, the Federal Criminal Police Office said there were 4,289 cases of people being threatened with firearms - the lowest level since 1993.

Last year there were 57 gun murders, up slightly from 42 the previous year.

Certain gun owners, such as marksmen and hunters are required to have public liability insurance.

All fully-automatic weapons are banned.

Semi-automatic weapons not intended for hunting are also banned.

Pump-action shotguns with pistol grips, or sawn-off shotguns are also banned.