Barcelona's old city has been overrun by outlets selling cannabis paraphernalia that are getting around tight zoning restrictions by registering as florists, disgruntled shopkeepers say.

In recent years, so-called weed shops have sprung up all over the city but are mainly concentrated in Ciutat Vella, the oldest part of the city and the area most popular with tourists.

Over the past six years, 118 new 'florists' have opened in Ciutat Vella, compared with just 21 in the rest of the city. Barcelona's florists' association says it is unaware of any boom in flower selling, and the number of florists in the city has been stable for years.

It is thought that there are as many as 250 weed shops in the city selling bongs, hookahs, seeds, and cannabis oil (CBD) products.

Cannabidiol (CBD) is extracted from marijuana plants and is sold legally in many countries for the treatment of anxiety, insomnia, and other conditions. The World Health Organization has reported "no evidence of public health-related problems associated with the use of pure CBD."