In pictures: Damascus 'chemical weapon attacks'

A man, who Syrian opposition activists say survived a chemical weapon attack, rests in a mosque in Douma, Damascus (21 August 2013)

Syrian opposition activists say hundreds of people have been killed on the outskirts of the capital, Damascus, after extensive shelling by government forces.

Image provided by Syrian opposition activists purportedly showing man and woman mourning next to bodies wrapped in shrouds in Irbin, Damascus (21 August 2013)

The main opposition alliance, the National Coalition, said the number of dead had reached more than 1,000 in what it described as a massacre.

Image provided by Syrian opposition activists purportedly showing victims of chemical weapon attack in Douma, Damascus (21 August 2013)

Witnesses claim poisonous gas was used, but the Syrian army says the accusations have been fabricated.

Image provided by Syrian opposition activists purportedly showing a girl receiving treatment at a makeshift clinic in Irbin, Damascus (21 August 2013)

Video footage and photographs have been posted online appearing to show civilians, including children, suffering the effects of a chemical agent.

Image provided by Syrian opposition activists purportedly showing victims of chemical weapon attack in eastern Damascus (21 August 2013)

The head of the United Nations team of chemical weapons inspectors currently in Syria, Ake Sellstrom, says they are ready to investigate the allegations and there have been calls for the Syrian government to grant them access.

Two girls, whom Syrian opposition activists say survived a chemical weapon attack, at a hospital in Douma, Damascus (21 August 2013)

The UK said it would refer the issue to the UN Security Council, while France said the perpetrators of such “intolerable acts” had to be held accountable.

Syrian security forces check ID documents at a checkpoint on Baghdad Street, Damascus (21 August 2013)

The Syrian foreign ministry said the allegations that chemical weapons had been used by government forces were false, and an attempt by the opposition to influence the UN inspectors and prevent them from carrying out their work.