Chocolates and bagged snacks are being taken off shop shelves after the discovery of potentially cancer-causing toxins in a batch of rice flour.
Several products have been pulled off the shelves
Three brands of products are being recalled because aflatoxin B1 was found at levels above the legal limit.
Aflatoxin B1 occurs naturally in mould but is linked to cancer in animals.
The Food Standards Agency said Quaker Caribbean Chicken Seasons, Sainsbury's Chocolate and Toffee Crispie Bites and Smiths Bacon Fries were affected.
Only batches with specific sell-by dates are being recalled.
A Food Standards Agency spokesman said: "The risk from occasionally eating small amounts of aflatoxins is likely to be very small.
"However, aflatoxins have been shown to cause cancer in animals and there is also some evidence to suggest they may be harmful to people. Therefore, we want to keep people's exposure as low as possible."
Smiths Flour Mills, a subsidiary of Northern Foods, discovered the contamination during routine testing of its rice flour.
The company reported it to the Food Standards Agency and stopped any more flour from the affected batches entering the food chain.
It is thought the contaminated rice originated in Pakistan and was imported into the UK from Sweden.
The Food Standards Agency is working to establish levels of contamination in the affected products.
The spokesman added: "The agency has requested companies to recall any products where the levels of aflatoxins in the final product would exceed the legal limit."
That limit in rice and processed products containing rice is two parts per billion.
Rice flour is used in food production as a thickener or to produce the crispy texture in products such cereals and crackers. It also makes the crisped rice used in some chocolate bars.
The affected products including their best before dates are as follows:
Quaker Caribbean Chicken Seasons - sold in single 28g packs and multipacks of four 25g packs - with best before date: 02-09-06 (batch no. GBB 602 131).
Sainsbury's 18 Chocolate & Toffee Crispie Bites - 216g pack with best before dates: 18-08-06 and 27-08-06.
Smiths Bacon Fries - sold on display cards with 24 packs (25g per pack) with best before dates - 09-09-06 (batch no. GBP4XX 111 or 112), 16-09-06 (batch no. GBP4XX 113 to 119 inclusive), 23-09-06 (batch no. GBP4XX 120 to 124 inclusive).