Syrian activists say a government air strike has killed at least 18 people in a residential area in the country's north, while a car bomb has killed five people in a Damascus suburb.
The activists said women and children were among those killed in Monday's air strike in the town of al-Bab. They said other people were feared dead under the rubble of damaged homes.
The activists said the car bombing in the Damascus district of Jaramana also wounded at least 27 people.
UN-Arab League Envoy: 'A terrible weight'
On the diplomatic front, international peace envoy Lakhdar Brahimi said in an interview with the BBC that he faces a nearly impossible task in trying to resolve Syria's 18-month conflict between President Bashar al-Assad's government and rebels fighting to end his 11-year autocratic rule.
The Algerian diplomat said 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," but that the lack of international action as people in Syria continue dying "is a terrible weight."
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.
French Foreign Minister Laurent Fabius said any use of chemical or biological weapons by Assad's forces against the Syrian opposition will trigger a "massive response" from Western powers who want him to step aside.
Fabius said in broadcast interviews Monday there is broad agreement about such a response, calling chemical weapons "a very big danger."
ICRC lobbies for access
Meanwhile, the new head of the International Committee of the Red Cross was traveling to Syria for a meeting with Assad to seek government permission for humanitarian access to civilians caught up in the conflict.
In a statement released ahead of his trip, Peter Maurer said it is of "utmost importance" for the Red Cross and its local partner, the Syrian Arab Red Crescent, to significantly scale up the humanitarian response at a time when more civilians are being "exposed to extreme violence." He said an adequate response is required to keep pace with humanitarian needs that have been growing "exponentially."
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.