Turkish Foreign Minister Ahmet Davutoglu said Thursday a "red line was crossed" in Syria and called for international action following reports of a massacre involving chemical weapons.
"We call on the international community in this situation where the red line was crossed long ago to intervene as soon as possible," he said in Berlin after talks with his German counterpart Guido Westerwelle.
Davutoglu said the United Nations Security Council had been too hesitant in the face of the bloodletting in Syria.
"If we don't manage to pass sanctions, we will lose the power to create a deterrent," he said, speaking through an interpreter.
"If we don't act decisively, even worse massacres will follow."
Westerwelle said the reports of the use of chemical weapons by the Syrian regime were still unverified.
"But if they were to be confirmed that would be monstrous," he said.
He called for UN weapons inspectors "to be granted immediate access to investigate the allegations".
The main Syrian opposition group claims that as many as 1,300 people were killed in a chemical weapons attack Wednesday on rebel areas near Damascus.
Videos distributed by activists, the authenticity of which could not immediately be verified, showed medics attending to suffocating children and hospitals being overwhelmed.
UN Security Council members are seeking "clarity" on the suspected chemical weapons attack.
But diplomats said the council did not adopt a formal declaration because of opposition from Russia and China, which have for the last two years blocked any condemnation of their ally in Damascus.
Westerwelle said he "regretted" the Russian and Chinese position, saying it met with "incomprehension" from Western powers.