A United Nations team is due to visit Syria on Thursday to discuss arrangements for the possible deployment of peace monitors.
About 250 observers are due to go there under a peace plan put forward by the UN and Arab League special envoy Kofi Annan.
However, there will be no deployment until steps are taken to end the violence between the security forces and opponents of President Bashar al-Assad.
Meanwhile, activists say troops have launched fresh assaults on rebels and several towns including Homs, Deraa and the capital Damascus have been shelled.
