Tallinn is the first EU capital to offer its residents free public transport, and though the move aimed at driving down car pollution is proving popular, visitors feel let down and others are accusing City Hall of a campaign gimmick.

Since the start of the year, hopping on a bus, tram or trolleybus has become a fare-free proposition for Tallinn's 420,000 residents. All they must do is validate a special pass proving they are eligible.

Pavel Ilmjarv, a 19-year-old student, says it's taken a while to get used to the new routine of swiping his pass against a special reader at the start of each journey.

"It's such a new thing, I often forget to do it," Ilmjarv said, adding he previously didn't need to swipe his monthly bus, which cost 23 euros.

"I'm not complaining, I love it," he said, a sentiment echoed by the vast majority of resident commuters.

With Estonia's average monthly salary at about 900 euros and around half the city's population relying on public transport, a family of four could save hundreds of euros in transport costs each year.

But it's a different story for non-residents.

As a Tallinn University student from Estonia's coastal resort town of Parnu, Eve -- who did not want to provide her last name -- doesn't qualify for a free ride. Even though she lives in the capital, her registered hometown is outside the city.

She gets an 8.50-euro student discount on the standard 23 euro pass. Meanwhile, visitors must shell out 1.60 euro per ticket.

"People from rural areas generally earn less than those in capital. I believe that in such a small state, transport in the capital where many people have to come not only for shopping, but also to visit state offices, should be free for everyone," she told AFP at a tram stop in front of the university.

For non-Tallinners, the fine for being caught riding without a ticket could be as much as 60 euros -- almost equal to Estonia's monthly unemployed benefit.

Joblessness in this Baltic state of 1.3 million which broke from the Soviet Union in 1991, joined NATO and the EU in 2004 and the eurozone in 2011, is hovering around 10 percent.

Toomas Pirn, a spokesman for Tallinn City Hall, says the free pass is already encouraging residents to leave their cars at home, easing both pollution and congestion in the picturesque, historic city centre.

"We hope to limit the number of cars on streets, and via that, the pollution of city air. Studies have shown that in Tallinn cars pollute the air most," Pirn says.

About half of all Tallinners have already taken advantage of the free public transport, he says, noting the project will cost the city around 12.4 million euros per year -- about a quarter of its annual public transport budget.

Data collected from usage of the special resident passes has caused some to raise privacy concerns.

The Estonian Data Protection Inspectorate has warned people's personal information and journey habits could be compromised, because the city intends to keep records of their movements for up to seven years.

Others believe City Hall, governed by the left-leaning Centre Party, is more interested in currying voter support ahead of a municipal election this October than in fighting pollution.

Nothing of the sort, insists Deputy Mayor Taavi Aas.

He hopes the European Commission will soon name Tallinn as Europe's Green Capital, a title held this year by Nantes in France before going to the Danish capital Copenhagen in 2014.

"We're seeking the title for 2018 and hope that being the first EU capital offering a free ride to all city residents is among steps that helps us to get it," he told AFP.