Croatia is toughening a public smoking ban after a six-month grace period for small bars and cafes expires at midnight (2200 GMT), local papers reported on Friday.
As of Saturday, smoking will only be allowed in cafes and bars smaller than 50 square metres (538 square feet) if they have installed a special ventilating system, they said.
In larger establishments and in restaurants smoking is allowed only in specially designated zones covering up to 20 percent of their total surface. Smoking is not allowed in any areas where food is served.
Croatia introduced a strict smoking ban for all public places in May 2009, sparking strong protests by managers of cafes and restaurants who claimed it was ruining their business.
The government ceded to their pressure and in September amended the law a giving them a six-month transitory period to meet the criteria.
According to health ministry figures, only 156 cafes out of about 350 that have requested permission to become a smoking establishment have received approval to do so.
Zlatko Puntijar, head of a national association gathering around 16,000 owners in the industry that employs some 100,000 people, said the few demands could be explained by the high costs of installing ventilating systems.
Fines for those breaking the law range between 500 and 15,000 kunas (69 and 2,600 euros, 93 and 2,700 dollars.)
The authorities have said the law is aimed at protecting non-smokers, who make up 68 percent of the country's population of 4.4 million.
The Balkans are home to Europe's most inveterate smokers, with 30 to 40 percent of all adults hooked on the habit, according to the World Health Organisation.