Ann Summers, the sex shop chain, has pulled thousands of novelty chocolate products from its shelves and website after tests revealed they were contaminated with the industrial chemical melamine.

The Food Standards Agency issued an alert over chocolate willy spread, a related nipple spread and a novelty pen set, which contains a chocolate-flavoured body pen, all of which were imported from a Chinese manufacturer called Le Bang.

Food safety experts detected levels of melamine were up to 100 times greater than limits set by the European commission.

Milk products contaminated with melamine have been at the centre of a health scare in China, after a number of children died from baby formula laced with the chemical. European food safety officials have imposed strict checks on food products arriving from China that contain milk products. Any found to have more than 2.5 milligrams a kilo must be destroyed. Tests on the Ann Summers products found levels up to 259 milligrams a kilo.

The FSA said the withdrawal was precautionary and the risk was low. "This is a first. We've never had to put out an alert before on willy spread, chocolate-flavoured or otherwise," it added.

Ann Summers said: "As a responsible retailer we have tested all of our chocolates and even before the FSA alert was issued had taken all relevant steps to remove the chocolate willy spread product that could be affected by this issue."