UK mattress companies Silent Night and newly-listed Eve Sleep have had to halt production at factories after being told there was a risk of excessive levels of a carcinogenic ingredient in its foam mattresses.

German chemicals giant BASF wrote to mattress makers and 48 other companies earlier this week to say that it had found that an ingredient it produced, TDI, contained unusually high levels of toxic ingredient dichlorobenzen following a "technical error".

Dichlorobenzene is an organic compound that is toxic to water organisms and can cause irritation of eyes, skin and respiratory tract in humans and is suspected of causing cancer, the company said.

TDI is a chemical precursor needed to make upholstery in furniture, such as foam mattresses and car seats.

Silent Night shut down production at one of its factories to perform emergency checks on its mattresses while it investigated the situation.

Former Prime Minister David Cameron visiting a Silent Night factory

"Following this thorough investigation, we can confirm that there has been no impact whatsoever on the quality or safety of any products manufactured at our Silentnight Group sites," a Silent Night spokesman said. "While we have now resumed manufacturing, there is likely to be some disruption in the short term."

Meanwhile, Eve Sleep is understood to have halted production at the German factory which supplies the company while checks were performed. 

"Eve’s UK and French products are produced in the UK using a separate supply route and were therefore never potentially affected," said a spokesman. "As a precaution, manufacturing was suspended immediately at the German factory, which supplies Eve’s European customers (excluding the UK and France). We can now confirm that all our products are completely unaffected and absolutely safe for customers.”

Rival Simba Sleep, which sells memory foam mattresses, said that initial checks found that it would not be affected by the cancer scare.

BASF said that it had now conducted initial tests on the foams with higher levels of the toxic ingredient. It found that "health hazards are not anticipated for consumers" and that two-thirds of the foam had not been processed through supply chains.

 "The withdrawal of the product has started in close cooperation with the customers," the company said. "BASF is in close contact with the relevant associations for mattresses and foam producers in order to find a solution as quickly as possible."