France has banned the online sale of nicotine products and limited their sale in pharmacies, after researchers suggested that nicotine may play a role in protecting against coronavirus.
The new rules cover products like nicotine gum and patches, designed to help people stop smoking.
Last week, data from a Paris hospital indicated that smokers were statistically less likely to be admitted for treatment for Covid-19.
Trials are set to continue in France.
France has reported nearly 22,000 coronavirus-related deaths since the start of the outbreak earlier this year.
The authorities are planning to gradually lift the lockdown from 11 May.
What are the new nicotine restrictions?
The French government says people will only be allowed to buy one month's supply of these products.
This can be done only through pharmacies - with a register taken of everyone who purchases them.
The aim is to stop people putting too much nicotine into their bodies, in the hope of protecting themselves against coronavirus, and also to protect the supply for people who need it, says the BBC's Lucy Williamson in Paris.
What's the background to this?
The run on nicotine products was sparked this week after researchers noticed the low number of smokers among those hospitalised with Covid-19.
The theory that nicotine could play a role in blocking the virus is due to be tested at a hospital in Paris, using nicotine patches.
The government's chief health official said the study was interesting but warned that smoking killed 75,000 people a year in France.
The official also warned that smokers who did become infected with coronavirus tended to have more serious symptoms.
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