France and Italy decided Thursday to postpone a planned closure of the Mont Blanc tunnel to avert traffic chaos after an alternative tunnel was closed by a landslide, Italian ministry sources said.

Matteo Salvini, Italian Deputy Prime Minister responsible for transport, and his French counterpart Clement Beaune, had agreed "the Mont Blanc tunnel will not close on Monday" as planned.

The planned works will "probably be postponed until September 2024", the source said.

The Mont Blanc tunnel had been due to close to traffic from September 4 to December 18 to allow heavy maintenance work.

Hundreds of cars and trucks pass through it every day, as well as through the Frejus tunnel.

But the Frejus tunnel was closed to vehicles over 3.5 tonnes last week until further notice after a landslide in the Maurienne valley, an artery between France and northern Italy.

Rome had pressured Paris to postpone the closure of the Mont Blanc tunnel to avert bottlenecks.

"The Frejus tunnel is closed due to the landslide, Mont Blanc risks closing due to works... We really risk congestion", Salvini said Thursday.

"The goal is to reopen Frejus as soon as possible but I asked (Beaune) for a favour to postpone the work on Mont Blanc or else there will be chaos."

According to the Italian ministerial sources, the formal decision on the postponement of the Mont Blanc works will be taken on Monday.