The Vatican is getting tough on smokers, banning staff from smoking in offices from Monday onwards.
The ruling applies to everyone from cardinals to cleaners, and comes on top of an existing ban on smoking in public places.
Effectively, smoking will now be banned indoors throughout the world's smallest state.
The tiny Vatican police force has the power to impose a 30-euro ($30) fine on any offender.
'Prohibetur Uti Fumo'
Pope John Paul II, a non-smoker, approved the new measure on 4 June.
The law stipulates that "No Smoking" signs should be put up around the Vatican, fuelling speculation that they will be in Latin, the official language of the Catholic Church.
If so, they would read "Vetatur Fumare" (No Smoking) or "Prohibetur Uti Fumo" (the use of smoke is prohibited), speculates Father Reginald Foster, a Latin scholar who translated the Vatican's cash point machines from Italian into the language of ancient Rome.
The law does not mention whether the sale of cigarettes in the Vatican's shop will continue.
Prices in the shop, which is reserved for the state's 4,000 employees, are around half those in Italian shops.
Italy's fines
An Italian priest, Ugo Mesina, denounced the sale of cigarettes in the Vatican in a 1995 speech before the Pope and about 500 Roman priests.
Anti-smoking laws in Italy are already tough, with police issuing on-the-spot fines of up to $250 for smoking in public places.
All recent popes have been non-smokers, though the popular "smiling pope" John XXIII, who died in 1963, was a cigar smoker in his youth.