The advice comes as the Met recorded a 57% increase in crimes involving shotguns in its area in the past year.
In total, 165 crimes involved shotguns in London between January and July 2009.
Earlier this month, Colt Welch was jailed for five years after shooting at police with a sawn-off shotgun during a car chase in north London.
It emerged that he was using a 12-bore that had been stolen from the gun cabinet of a house in Surrey while the licensed owner was away on holiday.
Detective superintendent Gary Donnison, from the Met?s anti-shooting unit, Operation Trident, said: ?The lower cost of ammunition, the ease of use and the absence of viable alternatives means that shotguns are being used by criminals as an accessory to their crimes. There has been significant success in seizing firearms such as handguns and pistols, and it is possible that the success is forcing criminals down a different avenue.?
The police contend they have seen an increase in the number of shotguns stolen from licensed owners. A total of 45 shotguns have been recovered by police in London since January, however, not all of these are linked to thefts from licensed shotgun holders.
Despite this, Det Supt Gary Donnison continued: ?We urge all owners of shotguns to ensure that they take every care to store and transport their guns correctly and remind them of their responsibility in legally owning a shotgun. It is vital that we prevent them falling into the wrong hands.?
While the police argues it is encouraging extra vigilance over security among law-abiding shooters, many in the shooting community have expressed their anger that the Met?s actions have done little to draw a distinction between the legitimate shooting community and the criminal use of guns.
This was reinforced by comments reported last week in the media, including the following on London-based news website, The Londonist: ?To the 24,000 shotgun licence holders in London, we say: ?Please lock up your guns. They?re really fricking big things.??
On the BBC?s Farming Today programme last week, a Met police spokesman appeared to blur the line between legitimate shotguns and illegal guns when he confused the two types as follows: ?The shotgun is the preferred weapon of older members of criminal networks because it is so fearsome once it is sawn off? there?s been a slow increase in their usage within the conventional criminal networks that you would attribute to the most serious levels of crime within the capital ? in the past two weeks our teams have recovered MAC-10 machine pistols, semiautomatic handguns.?
In a letter to Shooting Times magazine, reader Paul Harding, who heard the Farming Today programme, makes the following observation: ?Perhaps the Met Police should concentrate on closing down the route of import for illegal weaponry, and targeting urban crime gangs. I understand that both these tasks are difficult, and maybe that is why their attention has switched to the legal gun owning community, as they already have their details and home addresses, and don?t have to look too hard to find them.?