“It will depend on whether any UN member state goes to the secretary-general and says we should look at this event,” Sellstrom told TT from Damascus. “We are in place.” Just hours after Sellstrom made the comments, French President Francois Hollande said in a regular cabinet meeting that the latest allegations of a chemical attack “require verification and confirmation,” according to government spokeswoman Najat Vallaud-Belkacem. Vallaud-Belkacem said Holland would ask the UN team to go to the site “to shed full light” on the allegations. CBS News correspondent Holly Williams reported, however, that it wasn’t immediately clear whether the Syrian government would grant the UN team access to the Ghouta suburbs to gather evidence. Ahmed al-Jarba, the head of the Western-backed Syrian National Coalition, and the London-based Syrian Observatory opposition group also called on the U.N. team to investigate the incidents. Hamish de Bretton-Gordon, a British expert in chemical and biological weapons, told CBSNews.com on Wednesday that, based on the reported death tolls and the available video evidence — which he stressed he could not authenticate independently — it appeared that a weapon of mass destruction like Sarin gas was probably involved. In many of the smaller-scale attacks across Syria, de Bretton-Gordon has said small quantities of Sarin, or far weaker organophosphate compounds, could have been to blame, and it is feasible that poorly-trained rebel forces could have been behind such attacks. “Sarin is 4,000-times more powerful than organophosphates,” he explained, suggesting that if the toxic gas was used Wednesday on a large scale, it was “very unlikely” that opposition fighters could have been behind the attacks, as they “just don’t have access to that level of chemical weapons and the delivery means” needed to disperse them so widely. Damascus, the sprawling ancient capital city and President Assad’s base of power since the conflict erupted, had come under increasing pressure from rebel forces, which had tried to advance on the city center primarily from the east. Baghdadi reported that, according to eyewitnesses, the fierce military offensive began around 7:00 a.m. on Wednesday. One man said he counted about seven air raids and dozens of shelling targeting the district of Jobar, less than one mile from a main square in the capital. On Sunday, the 20-member U.N. chemical weapons team, led by Sellstrom, arrived in Damascus to investigate three sites where chemical weapons attacks allegedly occurred. The sites they were meant to probe are the village of Khan al-Assal just west of the embattled northern city of Aleppo and two other locations, which are being kept secret for security reasons. The Syrian government has always denied claims by the opposition of chemical weapons use, saying rebels fighting to overthrow Assad’s government have used such weapons.