(ANSA) - Milan, November 20 - Twelve enormous pink snails have moved in to Milan city centre for a new outdoor art installation designed to encourage the fast-living residents of the Lombardy capital to slow down.

Three metres long and two metres high, the huge molluscs are currently circling Piazza Scala in front of Milan's famous opera house and the nearby square in front of the Church of San Fedele.

Passers-by have been unable to resist stopping to touch the bright pink snails made from recyclable plastic, whose tentacles are perkily extended to the sky.

''Speed isn't always a virtue,'' explained Milan's culture councillor Massimiliano Finazzer Flory, who championed the installation by the Italian Cracking Art group.

''We need to play with the city to break with our obvious daily urban routine and rediscover the experience of moving about the city.

''These snails are in the streets not only as an invitation (for people to) slow down, but also to listen, since their shape is reminiscent of an ear,'' he added.

Once the snails have had their fill of the opera, they will start moving towards the square in front of Milan's Palazzo Reale before making their way in single file to the central train station in January.

The city council then plans to send them abroad to Amman, Tel Aviv and Chicago - three cities that are twinned with Milan - before bringing them back to form a 120-strong snail army for the Expo the city will host in 2015.

Currently comprising three Italians, two Belgians and one French designer, the Cracking Art group has been introducing giant brightly coloured plastic animals into cities worldwide since 1993.

The group claims its aim is to change the history of art through its strong environmental commitment and the revolutionary use of plastic materials to evoke ''the close relationship between natural life and artificial reality''.

Its outsized creations have invaded art galleries and public spaces, but also more unusual places such as supermarkets and motorways.

During the meeting of Group of Eight environment ministers in Siracusa earlier this year, the group was responsible for families of bright blue sea turtles - the animal chosen as the symbol of the G8 summit - crawling over the pavements of the seaside city.

Last year it was also behind the appearance of two gigantic orange rabbits nestling next to each other under the shade of some trees at Paris's Petit Palais Museum as well as 34 glowing yellow penguins apparently admiring the view over the River Vltava at the waterfront Kampa Museum in Prague.

But one of the group's most impressive feats is their trick of suspending their creations in mid air.

In 2001 a flock of plastic seagulls were frozen in flight above pedestrians' heads in a cobbled street in Arezzo, while the following year another group of birds appeared to be flocking above a courtyard in Treviso.

The collective repeated the trick the same year with a school of large golden dolphins leaping through the air among the palm trees of Alassio, a town on the Ligurian coast.

Cracking Art's snails are in Milan until January 20.