Russia's government says UN chemical weapons inspectors are expected to return to Syria on Wednesday, Sept 25, BBC News reported.

Deputy Foreign Minister Sergei Ryabkov said they would investigate alleged chemical weapons attacks at Khan al-Assal, Sheikh Maqsoud and Saraqeb. The inspectors had been preparing to do so when chemical weapons were fired at suburbs of Damascus on August 21, killing hundreds of people.

Last week, they confirmed the nerve agent sarin was used in that attack.

The inspectors were not asked to ascertain who fired the artillery rockets which hit parts of the Ghouta agricultural belt, but Western powers have claimed that it could only have been Syrian government forces.

The Syrian and Russian governments have challenged them to present firm evidence, and instead alleged that rebels were responsible.

UN war crimes investigator say there have been 14 alleged cases of chemical weapons or chemical agent use in Syria since the uprising against President Bashar al-Assad began in 2011.

In July, the Syrian government agreed to allow UN inspectors to visit Khan al-Assal, Sheikh Maqsoud and Saraqeb, where both sides have accused each other of using chemical weapons.

Following a series of delays, the team led by the Swedish scientist Ake Sellstrom finally arrived in Damascus on August 18. They were preparing to travel north to conduct on-site inspections when the first reports of the Ghouta attack emerged.

After taking environmental, chemical and medical samples, and interviewing survivors and doctors between August 26 and 29, the UN inspectors flew out of Syria because it appeared increasingly likely that the U.S. would launch punitive military action.

However, the threat of strikes receded on Sept 14 when the U.S. and Russia agreed a framework for the destruction of Syria's arsenal of chemical weapons by the middle of 2014.

On Tuesday, Ryabkov told the Russian parliament that the UN inspectors were expected to resume their work imminently.

"We are pleased that our persistent calls for the return of UN experts to Syria for the investigation of other episodes have borne fruit," he said.

Last week, he criticized the UN inspectors' report, saying it was "distorted" and "one-sided", and based upon "insufficient" information.

Ryabkov also said on Tuesday that Moscow and Washington hoped this week to finish drafting a UN Security Council resolution backing the Syrian chemical weapons disarmament deal.

Russia would not accept a resolution that would automatically impose punitive measures under Chapter VII of the UN Charter if Syria did not comply with its obligations, he added.

"[U.S. officials] always mention that plans to punish Damascus remain in force. We draw certain conclusions from that and assume that the threat of aggression in violation of international law is so far only delayed."