The UN today supported growing international claims that a toxic "substance" was deployed last week in Syria, as Britain prepared to submit a draft resolution condemning President Bashar al-Assad's government for the alleged chemical attack.
The Arab League as well as Western powers have held Assad's forces responsible for using toxic agents to kill hundreds of people in the Aug. 21 assault near Damascus.
- Check for the latest updates on the crisis in Syria
- Harper, Obama want 'firm response' to Syria attack
Although Assad has denied allegations of chemical use, UN special envoy to Syria Lakhdar Brahimi said Wednesday that UN inspectors have collected evidence to indicate a chemical was deployed in last week's attack.
"It does seem that some kind of substance was used that killed a lot of people," Brahimi said. "This confirms how dangerous the situation in Syria is."
The UN team's first field testing was in the western Damascus suburb of Moadamiyeh on Monday. The journey was delayed by sniper fire, though the team was unharmed. On Wednesday, the UN's convoy of seven SUVs again left a hotel in central Damascus to resume inspections.
According to anti-regime activitists, the inspectors made their way this time to the Damascus suburb of Eastern Ghouta, which was affected by the alleged chemical attack.
Inspectors have not accused rebel fighters or government troops of using chemical weapons in an attack that Doctors Without Borders says killed 355 people. The UN team's mission is only to confirm whether such weapons were used.
To the White House, though, it's "undeniable" that the government is the only side capable of launching a chemical attack, according to U.S. Secretary of State John Kerry.
Also Wednesday, British Prime Minister David Cameron's office said in a statement it will put forward a draft resolution under Chapter 7 of the UN charter, amid ramped-up rhetoric from Western allies for building military action against Syria.
Cameron's office said Britain seeks a measure "authorizing necessary measures to protect civilians," and that military force is one of the options that can be authorized. However, any language that could be read as allowing a military strike is likely to face veto by Syria's allies, Russia and China.
Canada says suspected chemical use 'an outrage'
Canadian Foreign Affairs Minister John Baird has called the alleged chemical attack an "outrage" and Prime Minister Stephen Harper is conferring closely with U.S. President Barack Obama as the Syrian situation escalates.
A branch of the jihadist group Islamic State in Iraq and the Levant (ISIL) issued a statement pledging to punish Assad's forces by striking government targets in an impending assault. The threat was reported by the SITE intelligence group, which tracks online terrorist activities.
ISIL claimed to have met with eight Syrian factions about a series of massacres by government forces.
"The meeting factions decided to carry out the 'volcano of revenge' invasion in response to the regime's massacres against our people in Eastern Ghouta, the last of which was the chemical weapons massacre," SITE quoted the statement as saying.
"They have decided to strike the main joints of the regime in imprisoned Damascus, including security branches, support and supply points, training centres, and infrastructure," the statement said.
With files from Reuters, The Associated Press