The European Union demands that the UK enforce a ban on ‘chlorine chickens’ as part of a trade agreement between the two parties, The Guardian writes Tuesday on the basis of leaked documents.

With the requirement, Brussels wants to protect its own meat market and make a potential trade agreement between the US and the UK more difficult.

The Guardian writes that the clause was added to the EU negotiating mandate on the advice of France. It would state that the parties must monitor the “quality of food and the agricultural sector”. According to the British newspaper, the clause was supported by all EU member states.

With the clause, the EU wants to prevent the British from suddenly lowering food standards for a trade agreement with the US after the Brexit. A well-known doom scenario is the ‘chlorinated’ chicken: a chicken that is treated with chlorine after slaughter to prevent samonella infections. It could also mean that the British are going to use pesticides that are banned on mainland Europe.

In all likelihood, the European Commission will present on Tuesday the complete negotiating mandate that should form the basis of the negotiations between the EU and the UK.