The movement claims the money for the rail could be better spent elsewhere, such as education and healthcare.
They claim there is little demand for the rail and its only reason for existing is so private companies can profit from its construction, which they say will destroy much of the Susa Valley.
The hooded men, belonging to the most extremist wing of the No Tav movement, attacked the construction site in San Didero.
The protesters, about fifty in number, threw molotov cocktails, firecrackers, parcel bombs and stones at the police who responded with tear gas.
In the Baraccone area, they hooked the main gate with a winch and are trying to pull it down.
The attack is taking place in several places. In nearby Chiomonte, where the other construction site in Val Clarea is located, a group started to disguise themselves.
Rome and Paris have vowed to complete the TAV line connecting Turin with Lyon, despite the years-long and often violent protests.
ANSA
