France has said that the international community would need to respond forcefully if allegations that the Syrian government was responsible for a chemical attack on civilians proved true.
"There would have to be reaction with force in Syria from the international community, but there is no question of sending troops on the ground," Foreign Minister Laurent Fabius told French television network BFM on Thursday.
If the UN Security Council could not make a decision, one would have to be taken "in other ways", he said, without elaborating.
Opposition activists accused Syrian President Bashar al-Assad's forces of gassing hundreds of people, including women and children, in Wednesday's attack near Damascus.
The Syrian National Coalition said more than 1,300 people had died, while videos and photographs showed scenes of dozens of people foaming at the mouth and of bodies stacked up in morgues.
The Syrian government has strongly denied the use of chemical weapons, and state television said the accusations were fabricated to distract the UN investigators who are in the country to investigate the alleged use of chemical weapons in March.
Red line crossed
Western governments have demanded immediate access for the UN chemical weapons investigation team to the sites of the alleged attacks.
Turkish Foreign Minister Ahmet Davutoglu said a "red line was crossed" in Syria and called for international action.
"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 loss of life in Syria.
The United States, Britain and France are among around 35 countries that have called for Chief UN Investigator Ake Sellstrom to probe the incident.
Sellstrom was in talks with Damascus "on all issues pertaining to the alleged use of chemical weapons, including this most recent reported incident", a UN statement said.
White House spokesman Josh Earnest demanded that the inspectors be given "immediate access to witnesses and affected individuals" and "the ability to examine and collect physical evidence without any interference or manipulation from the Syrian government".
Washington has previously described chemical weapons use as a red line that might prompt it to intervene militarily in Syria.
What if confirmed would be the world's most lethal chemical weapons attack since the 1980s led to an emergency meeting of the UN Security Council in New York.
The UN body has called called for a prompt investigation into an alleged chemical weapons attack.
"There is a strong concern among council members about the allegations and a general sense that there must be clarity on what happened and the situation must be followed closely," Argentina's UN ambassador, Maria Cristina Perceval, told reporters after a two-hour, closed-door emergency meeting of the council.
UN diplomats, however, said Russia and China opposed language that would have demanded a UN probe.