The international community is demanding UN access to the site of an alleged chemical attack in Syria.
Syrian President Bashar al-Assad has said any talks with the United States would have to be based on mutual respect. Some 440,000 people in Syria are living under siege conditions, according to the UN.
A new rebel coalition, "The Army of Conquest," has started an offensive against the city of Idlib in northwestern Syria. The extremists have offered full amnesty to Sunni Muslims if they desert government troops.
In a US television interview, Syrian President Bashar al-Assad has said the "Islamic State" (IS) has continued to grow during the last six months, despite US air strikes. The terrorist group has also expanded over land.
Activists say Syrian government forces have dropped barrel bombs containing chlorine gas on a village southwest of Aleppo, killing six. The government is accused of carrying out a similar attack in April.