Moscow's Foreign Minister Sergey Lavrov said Russia, which has military advisers training Syria's military, has kept close watch over Damascus's chemical arsenal. He said the Syrian government has moved them from many arsenals to just "one or two centers" to properly safeguard them.
Lavrov also told reporters on a flight from an EU summit late Friday that countries in the region had asked Russia to convey an offer of safe passage to Assad.
Syria refuses to confirm or deny if it has chemical weapons but Damascus is believed to have nerve agents as well as mustard gas. It also possesses Scud missiles capable of delivering them.
The push by rebels in Hama province came days after they opened a new front against regime forces attacking checkpoints and army posts in the central region.
Activists and state media reported violence in different parts of Syria on Saturday including in the capital Damascus and the northern city of Aleppo, Syria's largest.
In Damascus, the state-run news agency SANA said gunmen assassinated Saturday Haider al-Sammoudi who works as a cameraman for the government's TV station. Several journalists working for state media have been assassinated over the past months.
In another development, 11 rebel groups said they have formed a new coalition, the Syrian Islamic Front.
A statement issued by the new group, dated December 21 and posted on a militant website Saturday, described the group as "a comprehensive Islamic front that adopts Islam as a religion, doctrine, approach and conduct."
Several rebel groups have declared their own coalitions in Syria, including an "Islamic state" in the embattled city of Aleppo.
The statement said the new group will work to avoid differences or disputes with the other Islamic groups.
Syrian authorities meanwhile handed over to Beirut three Lebanese citizens who were killed last month in a clash with Syrian troops shortly after they crossed the border. Syria has so far returned 10 bodies to the Lebanese authorities and says it has no more.