Marijuana-scented cards are being distributed across the UK in the hope that they will help people to literally sniff out crime.

The scratch and sniff cards, the initiative of independent crime-fighting charity Crimestoppers, are intended to help people identify illegal cannabis farms in their neighbourhood. Over the last two years police forces have seized more than 1m marijuana plants, with an estimated value of over £200m, and there was a 15% increase in cannabis farms in 2011/12.

Crimestoppers will be distributing the cards, which replicate the smell of the drug in its growing state, with the help of the police. The cards may smell of cannabis but anyone hoping for a cheap high will be disappointed. In a tweet, the charity was at pains to point out that they do not contain marijuana's active ingredient, THC.

The tweet said: "Have u received one of our scratch and sniff cards? #weedthesigns #cannabis No THC content, just raising awareness."

Crimestoppers' director of operations, Roger Critchell, said: "We are distributing scratch and sniff cards because not many people know how to recognise the signs of cannabis cultivation happening in their neighbourhood. Many are also not familiar with the established links between this crime and serious organised crime."

The UK National Problem Profile report on commercial cannabis cultivation (pdf), produced last year, identified that commercial or industrial properties are being used less and there has been a significant move towards residential dwellings over multiple sites to grow cannabis plants.

Among the areas targeted for distribution of the cards are West and South Yorkshire, London, Greater Manchester and Avon & Somerset, which have all been identified as the places with the highest number of cannabis farms in the UK. The Association of Chief Police Officers (Acpo) found West Yorkshire to have the most cannabis farms in 2010/12 with nearly 1,800, while South Yorkshire was second, with over 1,600.

Acpo's lead for drugs, Andy Bliss, said: "Closing down cannabis farms and arresting the criminals who run and organise them is a key focus in drugs policing. This is because we recognise that these farms are often run by organised criminals but also because they bring crime and antisocial behaviour into local communities causing real harm and leaving people feeling unsafe."