London: The British government is increasingly concerned there is evidence that chemical weapons have been used in Syria.
Foreign Minister William Hague said the claims must be urgently investigated and perpetrators held to account.
Hague also welcomed the UN secretary-general`s announcement of an investigation into the allegations and called on the Syrian regime to co-operate fully, allowing the UN team unfettered access, the BBC reports.
Meanwhile, soil samples gathered from random sites in Syria, have been smuggled to the UK for testing, British intelligence sources claimed.
The evidence suggested that `some use of chemical weapons`, but it is not clear by which side, the sources added.
Syria is believed to have stockpiles of mustard gas and the highly toxic nerve agent sarin.
Only a handful of countries have failed to sign the Chemical Weapons Convention (CWC), which internationally bans their use.