In a letter addressed to the Russian president, Vladimir Putin, the leader of the world's 1.2 billion Roman Catholics, reiterated his strong opposition to any military intervention in the country, writing that "armed conflicts … create profound divisions and deep wounds which require many years to heal".
The pope was understood to have written to Putin – one of the Damascus regime's key allies – in his capacity as head of state of the nation currently holding the G20 presidency.
The pontiff's spokesman, Federico Lombardi, denied a report in an Argentinian newspaper that he had contacted Syria's president, Bashar al-Assad.
In the latest salvo in a growing anti-war movement within the Vatican, Francis called on world leaders to seek a peaceful solution to the crisis.
Among those gathering in St Petersburg are the British prime minister, David Cameron, the Chinese president, Xi Jinping, and the US president, Barack Obama, who is planning a "limited" military strike on Syria.
The pope wrote: "It is regrettable that, from the very beginning of the conflict in Syria, one-sided interests have prevailed and in fact hindered the search for a solution that would have avoided the senseless massacre now unfolding.
"To the leaders present, to each and every one, I make a heartfelt appeal for them to help find ways to overcome the conflicting positions and to lay aside the futile pursuit of a military solution.
"Rather, let there be a renewed commitment to seek, with courage and determination, a peaceful solution through dialogue and negotiation of the parties, unanimously supported by the international community."francis ] [ pope ] [ vatican ]