Beirut - Eighteen people, including 12 women and children, were killed overnight by shelling in the Syrian town of Deraa, where the uprising against President Bashar al-Assad erupted 15 months ago, the Syrian Observatory for Human Rights said on Saturday.

Fighting was also reported in Damascus, Homs and other cities, killing 33 people overall on Saturday, the group said, showing neither side was respecting a U.N.-backed ceasefire, the failure of which has left outside powers divided on what to do next.

"We didn't sleep all night, the situation is a mess, all kinds of explosions and heavy weapons," said Adnan, a resident in the southwestern town of Deraa near the Jordan border.

"We could hear the blast from the rockets hitting in the neighborhood nearby. If we were afraid, you can imagine how afraid our children are," he said via Skype.

Two massacres of civilians in the last two weeks have added urgency to talks among foreign powers on what to do since the ceasefire, supposed to take effect on April 12, has failed to stop the violence.

Russian Foreign Minister Sergei Lavrov said Moscow - which has shielded Assad from U.N. sanctions pressure - was not opposed to his departure, but only against that outcome being imposed on Syria from outside.