Syria has reiterated denials that it used chemical weapons against its own people in Damascus as Britain and the US discuss plans for a military action in response to the attack.
Foreign minister Walid al-Moallem also warned the West that the regime would defend itself using "all means available" if attacked.
Moallem challenged Washington and London to provide evidence that Damascus was behind the death of hundreds of people in the rebel-held suburb of Ghouta.
"They say the Syrian army did this; I deny it utterly and completely," al-Moallem told a news conference in Damascus. "There is no country in the world that would use a weapon of mass destruction against its own people."
US Secretary of State John Kerry said there was "undeniable" proof of a large-scale chemical attack launched by Damascus, something president Barack Obama, had warned would signify crossing a "red line" for the regime.
The minister also maintained the government was cooperating and honouring all the pledges it made to the UN over allowing a team of inspectors into the affected area.
Moallem denied the UN convoy came under fire by a regime-sponsored sniper during its first trip to the site and said a second trip was being delayed because safety could not be guaranteed, due to disputes between rebel factions.
Damascus accused British foreign secretary William Hague of lying when he said traces of the use of chemical weapons had been removed by the regime.
"The Syrian army cannot remove anything because these areas are controlled by rebels," Moallem said.
"What the British foreign minister said is not based on the reality of facts. He wants to give wrong information about this."
Moallem accused US and Britain of disregarding the UN and breaking international laws by going ahead with a military operation not approved by the security council.
He claimed the West-backed military intervention will end up boosting Islamist groups linked to al-Qaida operating on Syrian soil. President Bashar al-Assad had earlier warned the US it will face a new Vietnam.
"[It will face] what it has been confronted with in every war since Vietnam: failure," Assad said in an interview published by the state-run Syrian Arab News Agency.
Activists say more than 1,000 people were killed in the 21 August attack. Doctors Without Borders put the death toll at 355.