Italy's premier says the G-20 summit in Russia is the "last opportunity" for negotiated and political solutions to Syria's civil war.

Italian Premier Enrico Letta, in St. Petersburg at the summit's start on Thursday, also urged host Russian President Vladimir Putin to "avoid" a final break with Washington over Syria.

Letta says concern over Syria has hit "maximum" levels. He said the Italian naval torpedo destroyer Andrea Doria was being deployed just off the Lebanese coast to protect and provide logistic support to the 1,100 Italian troops on U.N. peacekeeping duty in Lebanon, which borders Syria.

Italian media reported a second warship, a frigate, was also being sent to Lebanon's coast, but the Defense Ministry denied plans to deploy it. Italy says it won't join military intervention without U.N. approval.