A watchdog should examine why a chemical that can be used to make the deadly sarin nerve agent was sold by UK firms to Syria with Government permission, a senior MP said.
Supplies of sodium fluoride were exported between 2004 and 2010, during the build-up to the brutal civil war when Bashar Assad was believed to be stockpiling chemical weapons.
The substance is an ingredient of sarin, which UK experts have established was used in the attack on the outskirts of Damascus on August 21, in which the US says 1,429 people died, the Mail on Sunday reported.
The Department for Business, Innovation and Skills said there was "no evidence" the chemicals - which it licensed for export for use in cosmetics and healthcare - were diverted to weapons programmes.
"These licence applications, which pre-date the current conflict and EU sanctions, were rigorously assessed and determined to be for legitimate commercial use," a spokesman said.
The quantities involved were "commensurate with the stated end use", it said.
But the fact that such products were allowed to be exported at all has raised concerns and led to a call for an investigation by the House of Commons Committee on Arms Export Controls (CAEC)
Tory Richard Ottaway, who chairs the Foreign Affairs Select Committee, said: "Any sensible person would be concerned if an ingredient of sarin gas was exported from the UK to Syria.
"I think this is something for the committee."
The Department for Business, Innovation and Skills (Bis) granted a number of licences to specialist firms allowing them to deliver sodium fluoride to Syria before the current conflict and European Union (EU) sanctions. Five were issued in July 2004, September 2005, March 2007, February 2009 and May 2010, the year before the civil conflict erupted.