The government's food safety watchdog has ordered a fresh probe into an artificial sweetener found in more than 6,000 products after research re-ignited fears it may cause cancer.
The Food Standards Agency has commissioned a review of data on aspartame, found in a range of soft drinks and low-fat foods, following a study published last year which found that rats fed the additive suffered increased cancer rates.
Experts from the government's Committee on Carcinogenicity this month began scrutinising the research to decide if it posed a risk to humans. If they find the sweetener is a danger, it could be banned from use in food in the UK.
The move comes just weeks after another study carried out by researchers in Liverpool found aspartame could cause nerve damage in a combination of four common food additives.
Opponents of the artificial sweetener have now criticised the FSA for not altering its advice to consumers about it while it is under review.
They believe products containing aspartame should be withdrawn from supermarket shelves until the sweetener is given the all-clear.
But food industry leaders insist this would cause unnecessary panic among consumers, adding they would support the decision of the review.
A spokeswoman for the Food Standards Agency confirmed it had commissioned the review, adding the results would be sent to the European Food Safety Authority, which is also assessing aspartame's safety. "In July 2005, the results of an Italian study carried out by the Ramazzini Institute questioning the safety of the artificial sweetener aspartame were published.
"As part of the response to the new study, the agency commissioned the UK Committee on Carcinogenicity to review the article from the Ramazzini Institute. Based on current evidence on the safety of aspartame, the agency is not advising consumers who wish to choose foods containing aspartame to make any changes to their dietary habits."
European experts are studying the research and are expected to report back in May.
But Liberal Democrat MP Roger Williams believes aspartame should be banned in the UK before the European decision.
He said: "There should be a precautionary principle used here, as the risk is so large. It is very difficult for people to know how much aspartame they are consuming."