Pope Francis decried the state of democracy and warned against "populists" during a short visit to Trieste in Italy's northeast on Sunday ahead of a 12-day trip to Asia -- the longest of his papacy.

"Democracy is not in good health in the world today," Francis said during a speech at the city's convention centre to close a national Catholic event.

Without naming any countries, the pope warned against "ideological temptations and populists" on the day that France holds the second round of a snap parliamentary vote that looks set to see the far-right National Rally (RN) party take the largest share of the vote.

"Ideologies are seductive. Some people compare them to the Pied Piper of Hamelin: they seduce but lead you to deny yourself," he said in reference to the German fairytale.

"The culture of rejection creates a city where there is no place for the poor, the unborn, the fragile, the sick, children, women, the young," he regretted, urging facilitation of social participation from childhood.

Ahead of last month's European parliament elections, bishops in several countries also warned about the rise of populism and nationalism, with far-right parties already holding the reins to power in Italy, Hungary and the Netherlands.

Francis also urged people to "move away from polarisations that impoverish" and hit out at "self-referential power".

After Venice in April and Verona in May, the half-day trip to Trieste, a city of 200,000 inhabitants on the Adriatic Sea that borders Slovenia, marked the third one within Italy this year for the 87-year-old pontiff, who has suffered increasing health problems in recent years.

Since travelling to the French city of Marseille in September 2023, the Argentine Jesuit has limited himself to domestic travel.

But he plans to spend nearly two weeks in Asia in September visiting Indonesia, Singapore and the islands of Papua New Guinea and East Timor. (AFP)