It is not illegal to stock the seeds, sell them or purchase them.

However, a criminal offence is committed as soon as they are used to produce cannabis.

Dundee East MP Stewart Hosie said, “There does appear to be a loophole in the law.

“I can’t imagine any other reason to by them other than to grow cannabis.

“I will write to the Cabinet Secretary for Justice seeking clarification on the matter and if it is indeed the case try to get that loophole closed.”

The issue came to light this week when a 44-year-old man appeared at Dundee Sheriff Court and admitted producing cannabis at his home.

The man said he purchased the seeds from a city shopping centre and bought growing equipment before learning how to grow them from the Internet. He got one ounce from each of his eight nursery sized plants and smoked about six joints a day.

Sentencing was deferred for reports.

Elizabeth Campbell, the owner of one city shop selling seeds, said the current legislation that allows people to buy seeds but charges them for growing cannabis is unfair.

“It’s legal to sell them and it’s legal to sell the equipment used to grow them but it’s not actually legal to grow them — that’s just wrong and it’s all the government’s fault,” she said.

“And it’s not like the people buying them are growing warehouses full of cannabis for sale, its just a few seeds which are invariably used for the grower’s own consumption.

“They should just legalise it — especially given that drinking is a much bigger problem.”

Ms Campbell said she did not require a special license to sell the seeds.

“I usually order a half dozen packets which lasts around a month,” she said.

“I’m not selling them to hundreds of people or anything but there is certainly a demand for them.”

A staff member at another shop selling the seeds said there was “quite a high demand” and packets were retailing at up to £85.

“Of course we know what they’ll be used for,” she said.

“What else would they be used for?”

As part of its drug strategy, the government reclassified cannabis from class C to class B in January.

The maximum penalty for supply, dealing, production and trafficking is now 14 years imprisonment, while the maximum penalty for possession is five years imprisonment.

Anyone caught in possession of cannabis can be arrested and police can also issue a penalty notice for disorder, which carries an on-the-spot fine of £80.

A spokesman for Tayside Police said, “It is not illegal to possess, sell or purchase cannabis seeds as the seeds do not contain the active constituent tetrahydro-cannabinol (THC) and, therefore, contain no illicit drug.

“While cannabis seeds themselves are not covered under the Misuse of Drugs Act, legislation could be contravened where anyone was found to be selling the seeds alongside other items that could be used in the cultivation or misuse of a controlled drug.

“In such circumstances, the police would warn the seller and advise them to remove those items from sale.

“If they did not comply then officers could take further action.”