French Foreign Minister Laurent Fabius says Western powers would have a "massive" response to any use of chemical or biological weapons by Syrian President Bashar al-Assad's forces.
Fabius said in broadcast interviews Monday there is broad agreement about such a response, calling chemical weapons "a very big danger."
His comments come as the head of the International Red Cross travels to Syria for a three-day visit that will include meetings with Assad and other officials. The group says the talks will focus on the "rapidly deteriorating humanitarian situation" in Syria and the challenges in reaching those impacted by the conflict.
Meanwhile, the new United Nations-Arab League envoy tasked with bringing a peaceful solution to the Syrian crisis says he has "no illusions" that his job will be easy.
Algerian diplomat Lakhdar Brahimi said in an interview broadcast Monday by the BBC that he does not yet see any ways around the barriers that blocked the efforts of his predecessor, Kofi Annan, but that he will continue trying.
Brahimi says he realizes the difficulty of his task, and that success "should be possible."
Annan quit last month, complaining that he could not fulfill his mission due to international divisions on Syria and escalating attacks by both Syrian government and rebel forces.
Brahimi says the lack of international action as people in Syria continue dying "is a terrible weight."
Opposition activists are reporting more deaths Monday, saying a bombing by a Syrian warplane has killed at least 15 people in the northern town of Al-Bab.
This image made from video provided by Shaam News Network (SNN) and accessed by the Associated Press on Tuesday, September 4, 2012 purports to show people walking through rubble after shelling in Idlib, Syria.
Residents inspect the damage after what was said to be an air raid by Syrian government forces near Azaz, September 3, 2012.
A Syrian child stands next to rebel fighters checking a house that was damaged in bombing by government forces in Marea, on the outskirts of Aleppo, Syria, September 4, 2012.
A Syrian rebel fighter prepares his AK-47 before going on patrol in Marea, on the outskirts of Aleppo, Syria, September 4, 2012.
A view shows the wreckage after a car bomb exploded in the Jaramana district of southeast Damascus September 3, 2012, in this photograph released by Syria's national news agency SANA.
Civilians wait to receive food rations in the Bab Al-Salam refugee camp in Azaz. At the Azaz-Kilis crossing, Syrians described dire conditions for refugees still trapped on the other side of the border.
Syrian Hamzah Abu Bakri, displays portraits of his brothers who were killed last week while standing by their vegetable shop in Aleppo, Syria, September 2, 2012.
Boys play on a Syrian military tank (destroyed during fighting with the rebels), in Azaz, September 2, 2012.
A Syrian refugee hangs clothes to dry at Zaatari Refugee Camp, in Mafraq, Jordan, September 2, 2012.
Syrian barbers who fled their homes shave the heads of other displaced men at the Bab Al-Salameh border crossing, in hopes of entering one of the refugee camps in Turkey.
A civilian pushes a baby stroller containing his belongings as he flees the El Edaa district in Aleppo, September 2, 2012.
Some information for this report was provided by AP, AFP and Reuters