* Traffic to be blocked off around ancient sites
* Decision sparks anger from motorists, local businesses
* Bicycle-riding mayor wants to protect ancient treasures
By Catherine Hornby and James Mackenzie
ROME, Aug 1 (Reuters) - Less than two months in office, the mayor of Rome is promising a minor revolution in the Italian capital and risking the ire of local motorists by closing the area around the ancient imperial forum complex to traffic.
The roads near the forum and the nearby Colosseum will be shut down on Saturday night for a special series of celebrations before being cut off permanently, starting from 5.30 a.m the following morning.
The decision has aroused heated opposition from residents and motorists who fear chaos from traffic diversions, but newly-elected mayor Ignazio Marino says Rome's incomparable but often neglected archaeological treasures go beyond local politics.
"I don't want it to be a matter for the district of Monti," the 58-year-old surgeon-turned politician said this week, referring to the city zone where the site is located. "I want it to be a matter for the whole world."
The mighty Colosseum and the so-called "fori imperiali", a series of overlapping public squares built over more than 100 years by successive Roman emperors, are among the city's most spectacular sites, drawing hundreds of thousands of tourists every year.
But the area has long been divided by a wide thoroughfare constructed under former fascist dictator Benito Mussolini which cuts straight through the ancient ruins and forms a major road artery in a city that strains to keep its traffic under control.
It is a familiar issue in Rome, where infrastructure projects including the expansion of the underground metro system have long been held up by the need to protect the archaeological treasures that lie everywhere beneath the city streets.
But Marino, a top liver transplant specialist with long experience of working in the United States, compares Rome with other European capitals such as Paris, Berlin or London and says it has to do more with its rich artistic and cultural heritage.
With Rome emptied of much of its normal traffic as it swelters in the heat of the August summer holiday, the full impact of the decision may not be felt immediately but already opposition is growing.
"This will just create more chaos," said Cinizia Perugini, who runs a newsstand in the area. "My customers are angry, they don't know how they will reach me anymore, and I don't even know how I will get to work," she said.
The ban will not stop all traffic around the sites. Buses, taxis, bicycles and emergency vehicles will still be allowed, although at reduced speeds, and there has been little detail about other changes to make life easier for pedestrians.
Marino, nicknamed "Rocky" by his university colleagues in Pittsburgh, has already established a distinctive profile in Rome by riding to appointments on a bicycle and he says he expects opposition to his plans.
Many residents complain that the decision was rushed through just weeks after the June election, which brought Marino to his office on the Campidoglio hill overlooking the forum.
Elvira Micieli, who owns a clothes shop on a road where traffic will be redirected, said she was worried about increased smog and new restrictions on parking which she feared would hit her business.
"The mayor should have spoken to residents and companies in the area first, then organised things such as extra parking space and better public transport," she said, adding that she had signed a petition opposing the plan.
"He can't just wake up one day and change everything so drastically, we don't live in a dictatorship," she said. (Editing by Gareth Jones)