Italy on Monday night risked pitching into political turmoil as projections of the result of its general election pointed to a hung parliament and confirmed that the anti-establishment Five Star Movement (M5S), led by an ex-comedian, Beppe Grillo, had exploded onto the national stage.

Projections suggested on balance that the centre-left would take the lower house, the Chamber of Deputies, by a tiny margin. But they also indicated that a resurgent right led by Silvio Berlusconi would have slightly more seats - though not necessarily more votes - in the Senate.

Crucially, it seemed certain that neither right nor left could obtain an outright majority in the upper house, where the balance would be held by the M5S. So far, Grillo has ruled out supporting either side in his drive to sweep away Italy’s existing political parties and the cronyistic culture they support.

Exceeding even the most adventurous pre-electoral predictions, the populist M5S was set to emerge as Italy’s biggest single party - a result that will send shock waves through the eurozone and beyond. Because it is running alone and not in a coalition, however, Grillo’s movement lagged the two big alliances in the number of seats.

The emerging result indicated that fresh elections were a strong possibility and, at best, foreshadowed a weak government unable to pass the tough reforms Italy needs to enhance its grim economic prospects.

European leaders have been desperate to see a stable government in Italy, and are likely to be horrified and aghast at the triumph of populism in the eurozone’s third biggest economy. The likely results threatens to reignite the question of the euro’s stability following months of relative calm.