Campaigners have called on high-profile bread manufacturers and supermarkets not to use wheat that is sprayed with glyphosate before harvest.

The Soil Association has produced a letter to retailers and bakers around the UK, following the European Commission’s verdict to lengthen the agreement for glyphosate weed killer use for 18 months.

Last year, the association set up the ‘Not in Our Bread’ campaign, after scientists claimed the widely used weed-killer was carcinogenic.

Bread trade bodies have stated that they take food safety “very seriously”’ and that glyphosate is only used to reduce the loss of crops.

Federation of Bakers director Gordon Polson told “The Federation of Bakers endeavours to continue working closely with their suppliers to ensure any incidence of residues remains low. We will follow all developments with regards to the safety of pesticides, including glyphosate, to ensure the upmost safety to consumers.”

The European Commission originally proposed a 15- year marketing licence for glyphosate, and the renewal of the authorisation has been fiercely debated since March 2015.

In August 2015, nearly 20,000 signatures were signed on a petition to stop UK bread manufacturers using glyphosate.