Turkey, which shares a border with Syria, and its allies are struggling for ways to pressure Syria into stopping the violence that focused in past weeks on the rebellious central city of Homs, where forces have blocked a Red Cross convoy from delivering badly needed aid to the neighborhood of Baba Amr.
Turkish Foreign Minister Ahmet Davutoğlu described the Syrian regime's actions as a "crime against humanity," in a remark that dovetailed with a commitment from the European Union on Friday to document war crimes in Syria.
But China and Russia have blocked action against Syria at the UN Security Council, and Iran remains a powerful ally of Syrian President Bashar Assad.
"No government, no authority, under no circumstances, can endorse such a total massacre of its own people," Davutoğlu said. "The international community must speak louder."
"The lack of international consensus is giving Syria the courage to continue," he said.
The Syrian uprising started with peaceful demonstrations, but now also consists of armed groups, including army defectors, that are generally outmatched by Syrian forces equipped with tanks and artillery.
The revolt has killed more than 7,500 people, according to the most recent U.N. estimate.
Syria describes its opponents as "terrorists," but the Turkish foreign minister noted how the crackdown had deteriorated from the shooting of civilians at protests to the indiscriminate shelling of neighborhoods.
"The situation in the field seems to resemble Sarajevo, or Srebrenica. This seems to be the way we are heading," Davutoğlu said at a joint news conference with Giulio Terzi, Italy's foreign minister.
"We believe that diplomatic pressure on the Assad regime must be increased," Terzi said. "We say this not only from the point of view of the EU. We believe all international institutions must do this."
He said the situation in Baba Amr, where Syrian authorities have blocked aid from reaching civilians, was "barbaric."
Both foreign ministers referred to the possibility of a solution modeled on Yemen, where former President Ali Abdullah Saleh handed power to a successor in a move intended to bring peace after more than a year of violent protests against Saleh's longtime rule.
But there is no indication that Assad is prepared to relinquish power, and some Syrian opposition figures are calling for more robust action from supportive nations, including the arming of outgunned rebels known as the Free Syrian Army.
On Friday, Davutoğlu met for four hours with Syrian opposition leaders in Istanbul. He said he advised them on what steps they should take, an apparent reference to the failure of the splintered opposition to organize into a cohesive entity.