Business Secretary Vince Cable has come under increased pressure over exporting potential chemical weapons components to Syria in breach of government policy.

Commons committees on arms exports controls chairman Sir John Stanley said January 2012 export licences for sodium fluoride and potassium fluoride should never have been approved.

And he demanded Mr Cable reveal the company involved.

The Lib Dem minister has told the commitee that the licences were granted in line with EU and British export rules, including over whether there was a “clear risk that they might be used for internal repression.”

EU rules were tightened following the introduction of new sanctions in June 2012 and the licences were revoked in July, but by that time some chemicals had already been shipped out.

In a strongly worded letter to Mr Cable, Sir John wrote: “Syria has long been know to be a holder of chemical weapons and your department were clearly fully aware that sodium fluoride and potassium fluoride are precursor chemicals in the manufacture of chemical weapons.”

Given that, he asked: “Do you agree on reflection that both of these licences should have been refused?”

Sir John also accused Mr Cable of misrepresenting Britain’s policy on export controls.

He cited a statement by Foreign Secretary William Hague who said that export licences were not issued in situations where they “might be used to facilitate internal repression.”

This was a “substantially different and materially tighter” policy than Mr Cable’s formulation, he argued.

Amnesty British arms programme director Oliver Sprague said: “Chemicals like sodium flouride and potassium fluoride are used in the medical and manufacturing industries, and these exports could have been completely legitimate.

“However, where the products are as sensitive as these, it’s vital that additional — and really rigorous — safeguards are put in place to ensure that the materials are not at risk of being converted for military or other unintended use.”