Legislation to control the sale of chemicals needed to make deadly Sarin gas would be "impractical and ineffective", according to the government.
A Sarin attack in Tokyo killed 12 people
Fears have been raised about the availability of ingredients which terrorists could use to make the nerve gas,
A BBC reporter was able to buy the ingredients for the gas using a credit card and fake headed note paper.
A spokesman for the Department of Trade and Industry said that many of the chemicals involved have legitimate industrial, commercial or household uses.
He said Sarin gas was strictly controlled under the international Chemical Weapons Convention (CWC), but many of the individual elements have "everyday" uses.
"Substances dangerous in themselves are subject to strict controls under the CWC.
"But to ban any substance that could be used in conjunction with others to make a dangerous substance would lead to economic meltdown.
"Many of these chemical ingredients have broad, everyday uses, for instance sodium chloride, which is used across a range of household products."
A Home Office spokesman that banning the sale of substances which are used safely and legitimately in daily life would be "doing the terrorists' job for them - by disrupting
industry and damaging our economy".
Every chemical supplying company needs to make sure that customers are legitimate.
Chemical Industries Association
He denied criticisms that Whitehall was not taking the threat posed by
terrorists seriously enough.
"The UK has some of the most stringent counter-terrorism laws in the world," he said.
"It is a criminal offence not only to possess chemical or biological weapons but also to provide, receive or recruit for training or instruction in the use of such weapons.
"If there was evidence that anyone was actively involved in terrorism, they would be arrested."
The Today programme's reporter Angus Stickler found that stringent and rigorous import and export controls were place on the ingredients by the government.
But there are no laws restricting the purchase of "chemical weapons pre-cursors" inside the UK.
The Chemical Industries Association, which operates a voluntary code of practice, said it was up to chemical companies to remain vigilant, to monitor suspicious enquiries and control who they employed.
Spokesman Steve Elliott said the chemical manufacturing industry had a strict code of conduct and "knee jerk" legislation would not help.
He said: "We are not against regulation. We are already heavily regulated and so we should be.
"We have made great efforts to ensure chemical plants are safe and now the issue is around how the products are traded.
"Every chemical supplying company needs to make sure that customers are legitimate."
He said: "I don't think there is a way of making it foolproof.
"A determined criminal will always find a way of accessing these chemicals. Just as a determined burglar will always find a way to break into a house."