More than a thousand people have demonstrated at the Mont Blanc tunnel to protest allowing heavy goods traffic to use the transalpine route.
The tunnel, the main trade link between France and Italy, was closed in 1999 following a devastating fire, which claimed 39 lives. It re-opened to traffic on March 9, 2002, but until now all heavy-goods-vehicles, (HGVs) were still prohibited.
On Monday, HGVs with up to four axles and weighing more than 19 tons were allowed back into the tunnel. It marked the latest stage of a staggered reopening schedule, which allowed cars into the tunnel in March and small trucks and tourist buses in early April.
However strict restrictions apply to HGV flow. There is a one-way traffic policy and the trucks are required to keep a significant distance from the vehicle in front throughout their 12-kilometre tunnel transit.
The traffic restrictions are something the Gotthard tunnel in Switzerland shares with its French counterpart. It too, has specific guidelines about how and when HGVs can use the tunnel following a fire in October last year, which killed 11 people.
But protesters, who demonstrated on the French side of the tunnel, say the resumption of heavy traffic flow will cause environmental problems such as increased levels of air pollutants and noise pollution.
As such, they carried signs with slogans saying the trucks were not welcome. Up to 300 police officers and a helicopter were brought in to combat any violent protest, but the demonstrators' actions remained peaceful.
The tunnel is set to re-open to all HGVs, except those with hazardous cargoes, on June 25.
For the past few months, the Italian government has repeatedly called for HGV traffic to have freer access through the Mont Blanc and Gotthard tunnels.
But Switzerland is standing its ground on the Gotthard, even though it has also come under pressure from domestic and international hauliers to ease restrictions.
swissinfo with agencies