Greeks were banned from smoking at work and inside bars and restaurants on Wednesday, but many question how the measure will work in Europe's heaviest smoking nation.

Terraces in central Athens filled up with smoking clients as tobacco is still allowed outside, and there was confusion over how the law will be applied indoors.

More than 3,000 bloggers joined an anti-ban Facebook group. "Guys don't worry, even police officers smoke here, no one will follow this law," one message said on http://www.facebook.com/group.php?gid=8127674862

But Health Minister Dimitris Avramopoulos said the ban will work, contrary to past failed attempts. "Today Greece turns the page," he told Greek media.

"It's the first time that this measure will be implemented, to end the myth that we make laws that we don't respect."

The law, which threatens hefty fines for offenders, bans smoking indoors in all public or private areas used for working purposes, including airports, taxis and buses. The law also bans the sale of tobacco to under 18-year-olds.

LAST-MINUTE AMENDMENT

A last-minute amendment allows offices where more than 50 people work to have designated smoking areas.

Restaurant and bar owners of properties of up to 70 square metres can decide whether their business is smoking or non smoking. Others can set up ventilated smoking areas.

Greece breaks all European records with more than 40 percent of the population smoking and six out of ten being exposed to smoking at work, according to a European Union poll.

Many doubt the ban can be implemented in a country where smoking is such an entrenched tradition.

"They even smoked today in here," 33-year-old bar-tender Errika Antili said, when asked if his regulars were abiding by the new rule. "Everybody smokes and I absorb the smoke," said Antili, who supports the ban.

Smokers breaking the law face a fine of up to 500 euros.

Businesses breaching it for the first time face fines of up to 1,000 euros. The fines go up for each repeated offence and businesses could be banned from selling alcohol or tobacco for up to three months on the third violation. The fourth time, the company's licence would be removed.

"We will remove the ashtrays and put them only on the outside tables for those who want to smoke, until we can understand what exactly (the law) states, because until now we don't understand it," restaurant owner Nikos Koutouzis said.

Smoking-related diseases kill about 20,000 people a year in Greece, costing the country 2.14 billion euros ($3.01 billion) a year, the Health Ministry said.