The British city of Bristol has become the country's first to test smoke-free zones in outdoor public places, without imposing an outright ban, officials said Monday.

The southwestern English city, named Europe's Green Capital for 2015, is running a pilot scheme in two squares.

Campaigners in favour of the move say they hope it will offer local people a healthier environment.

"These city-centre squares are often full of children playing and this pilot will provide a smoke-free environment for kids and their families to enjoy," said Fiona Andrews, director of Smokefree South West, the body which initiated the scheme.

But smokers' rights groups said the move, consisting of signs discouraging smoking, was coercive and bullying.

"It really is just going way too far. The authorities don't have a right to coerce and bully people into quitting smoking," Simon Clark of the Forest (Freedom Organisation for the Right to Enjoy Smoking Tobacco) group said.

Cities including New York and Hong Kong have already imposed outdoor smoking bans.