Kofi Annan, joint envoy of the United Nations and Arab League for Syria, has received a response from Syrian President Bashar al-Assad to his proposals, but questions remain and he is seeking clarification, a spokesman said on Wednesday.

"The Joint Special Envoy (JSE) for Syria, Kofi Annan, has now received a response from the Syrian authorities. The JSE has questions and is seeking answers," spokesman Ahmad Fawzi said in a brief statement issued by Annan's office in Geneva.

"But given the grave and tragic situation on the ground, everyone must realize that time is of the essence. As he said in the region, this crisis cannot be allowed to drag on," he added.