British companies sold chemicals to Syria that could have been used to produce the deadly nerve agent that killed 1,400 people,The Mail on Sunday revealed yesterday.
Between July 2004 and May 2010 the Government issued five export licences to two companies, allowing them to sell Syria sodium fluoride, which is used to make sarin.
The Government last night admitted for the first time that the chemical was delivered to Syria - a clear breach of international protocol on the trade of dangerous substances that has been condemned as 'grossly irresponsible'.
The sales were made at a time when President Bashar Assad was strongly suspected to be stockpiling the chemical weapons that have caused an international crisis.
The UK firms delivered sodium fluoride to a Syrian cosmetics company for what they claim were legitimate purposes. But intelligence experts believe President Assad's regime uses such companies to divert chemicals into its weapons programme.
Thomas Docherty MP, a member of the Commons Arms Export Controls Committee, said: 'These are very disturbing revelations uncovered by The Mail on Sunday regarding the provision of sodium fluoride to Syria. At no time should we have allowed President Assad's regime to get its hands on this substance.
'Previously we thought that while export licences had been granted, no chemicals were actually delivered. Now we know that in the build-up to the Syrian civil war, UK companies - with the backing of our Government - were supplying this potentially lethal substance.
'While the last export licence was issued in May 2010, these licences are obtained prior to manufacture and the industry standard is for four to five months to pass before the chemicals are delivered.
'So we are looking at late 2010 for the British supplies of sodium fluoride reaching Syria. The Government has some very serious questions to answer.'
The Department for Business, Innovation and Skills refused to answer questions regarding how much sodium fluoride was bought and sold - or which companies were involved.