More than 800 road bridges in France are at risk of collapsing within a few years, according to a survey carried out for the Transport Ministry that has raised alarm following the Genoa tragedy.

The July report, commissioned by the ministry from two private consultancies, predates the Italian motorway bridge collapse in which four French holidaymakers were killed on Tuesday, but French media have highlighted its findings this week.

It says that about 840 French bridges, a third of those maintained by the state, show evidence of damage that could present “a risk of collapse” if they are not reinforced.

The report also pointed out that bridges in France “are only repaired, on average, 22 years after the appearance of the first deterioration”.

Pressure is mounting on the government to specify which bridges are affected, but no list has so far been made public.

The Transport Ministry is playing down the danger. An official told France Info radio that there was no cause for panic. “When bridges are described as being in ‘poor or very poor condition’, you have to take into account that we are talking about fragility over the long term. No structures will be open to the public if they are not completely safe. If there is the slightest risk, action will be taken immediately.”