PARIS -- As Western powers pressed Syria to allow United Nations inspectors to examine the site of a possible poison gas attack outside the capital, Damascus, France said on Thursday that outside powers should respond "with force" if the use of chemical weapons was confirmed.
At the same time, Israel said its intelligence assessments pointed to the use of chemical weapons.
"According to our intelligence assessments, there was use of chemical weapons," the Israeli minister of strategic and intelligence affairs and international relations, Yuval Steinitz, told Israel Radio, "and this of course was not for the first time."
Mr. Steinitz did not specifically accuse the government of the Syrian president, Bashar al-Assad, of using chemical weapons on Wednesday, but in the past Israel has frequently accused pro-Assad forces of using weapons from their large stockpiles of such munitions.
In April, Israel's senior military intelligence analyst, Brig. Gen. Itai Brun, told participants at a security conference in Tel Aviv that the Syrian government had "increasingly used chemical weapons." General Brun said, "The very fact that they have used chemical weapons without any appropriate reaction is a very worrying development, because it might signal that this is legitimate."
In an interview with BFM-TV, the French foreign minister, Laurent Fabius, expressly ruled out the idea of ground forces' intervening in Syria's bloody civil war, now in its third year with more than 100,000 fatalities.
"There would have to be reaction with force in Syria from the international community," Mr. Fabius said, but "there is no question of sending troops on the ground."
He gave no further details of what he had in mind. During the Libyan revolt that overthrew Col. Muammar el-Qaddafi in 2011, France, then led by President Nicolas Sarkozy, joined with Britain in an air campaign that drew on strong support from the United States and other NATO allies.
The Obama administration has shown little appetite for comparable intervention in Syria. Indeed, America's top military officer has told Congress that while the Pentagon could forcefully intervene in Syria to tip the balance in the civil war, there are no moderate rebel groups ready to fill a power vacuum.
"Syria today is not about choosing between two sides, but rather about choosing one among many sides," wrote Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, in response to a congressman who asked for a detailed analysis of potential, but limited, options for punishing Mr. Assad's government in Syria. "It is my belief that the side we choose must be ready to promote their interests and ours when the balance shifts in their favor. Today, they are not."
In Paris, Mr. Fabius's remarks were made a day after diplomatic moves at the United Nations Security Council in New York produced a limited response to the claims by opposition forces on Wednesday. Their charges that scores if not hundreds of people had perished in the attack were supported by copious, if unverified, video images.
In an emergency session, the Security Council called for a prompt investigation of the allegations and a cease-fire in the conflict, but it took no further action. Mr. Fabius said that if the Security Council could not reach a decision, then action would have to be taken "in other ways," which he did not identify.
Throughout the Syrian crisis, France has taken a lead among Western nations in supporting the Syrian rebels, and its government was the first in the West to fully embrace a coalition of rebel forces last November.
The allegations of a gas attack were particularly jarring because a team sent by the United Nations is already in Damascus to investigate chemical strikes reportedly waged earlier in the war. The United States, the European Union and other world powers called for the investigators to visit the site of Wednesday's attack, which news reports said took place only a 15-minute drive from the inspectors' hotel.
The Security Council's caution provoked a harsh outburst on Thursday from Turkey, a bitter foe of Mr. Assad's government, which shares a long and porous border with Syria and has been at the forefront of efforts to support the rebels trying to overthrow him.
Speaking to reporters in Berlin, Foreign Minister Ahmet Davutoglu of Turkey said Thursday: "All red lines have been crossed, but still the U.N. Security Council has not even been able to take a decision. This is a responsibility for the sides who still set these red lines and for all of us."
If outsiders do not act, he said, they will lose the power to deter future attacks.
The notion of "red lines" was initially introduced last August by President Obama, who said the use of chemical weapons in Syria would radically alter American calculations about the war.
At the time, Mr. Obama declared that the use or deployment of chemical or biological weapons would "change my calculus" and "change my equation."
Speaking at a joint news conference with Mr. Davutoglu on Thursday, Foreign Minister Guido Westerwelle of Germany urged the authorities to give United Nations inspectors immediate access to the area where the attack was reported. "We are very worried about the reports that poison gas has been used near Damascus," he said. "These reports are very serious and if they are confirmed would be outrageous."
At the United Nations on Thursday, a spokesman for Secretary-General Ban Ki-moon said he had asked his top arms control official, Angela Kane, the high representative for disarmament affairs, to visit Damascus as part of an effort to secure the Syrian government's permission for the U.N. investigative team currently in the country to visit the attack site.
"The Secretary-General believes that the incidents reported yesterday need to be investigated without delay," the spokesman, Eduardo del Buey, said.
Alissa J. Rubin reported from Paris, and Alan Cowell from London. Reporting was contributed by Isabel Kershner from Jerusalem, Victor Homola from Berlin and Rick Gladstone from New York.
This article originally appeared in The New York Times.