Spain's Canary Islands is to ban smoking outdoors when social distancing cannot be guaranteed to curb the coronavirus. 

It comes a day after Galicia took a similar measure. 

The smoking ban will come into effect on Friday along with mandatory wearing of face masks in all public spaces, Canaries regional leader Angel Victor Torres said.

The Canary Islands, a tourism hotspot off northwest Africa, had been the only Spanish region where it was not obligatory to use face masks. 

Officials in regions including Madrid and Andalusia said they were considering similar smoking restrictions. 

"Smoking will not be allowed in open spaces, in places where there are crowds, if there is not sufficient social distance," Torres told a news conference, adding that terraces were included in the restrictions. 

Infected smokers could blow droplets carrying the virus when they exhale, he added. 

A smoking ban in the northwestern region of Galicia, best-known as the destination for pilgrims hiking along the Camino de Santiago, came into force overnight. 

The Galician law also forbids smokers from removing masks to smoke in public if it is not possible to maintain a distance of two metres between people, in what is believed to be the first such restriction in Europe. 

Galicia and the Canaries are among the least-affected regions of Spain, the country with the highest number of infections in Western Europe. 

'A bit disproportionate' 

The Spanish Society of Epidemiology in July called for smoking to be banned in outdoor spaces, arguing there was a risk that infected smokers who are asymptomatic "could release droplets" and "put at risk the rest of the population". 

Spain's regions are responsible for healthcare policy, which has led to a patchwork of measures to curb the virus. 

The World Health Organization has said tobacco users could increase the possibility of transmission of the disease since it involves contact of fingers with the lips. 

While the smoking ban was applauded by many medical experts, some questioned its effectiveness. 

"There is not yet enough solid scientific information to show that in open spaces, tobacco smoke can transmit the disease," Fernando Garcia, an epidemiologist at the Carlos III institute for health, told AFP. 

"To take such an extreme measure when there is not enough evidence, I think is a bit disproportionate."