Although the government can negotiate restrictions as part of a free trade agreement, Nick von Westenholz, NFU director of EU exit and international trade, said he doubted whether ethical or environmental concerns could prevent certain foods coming from other countries.

Animal welfare and environmental standards are not currently specified as permissible grounds for import bans - meaning other countries would quickly challenge such restrictions at the World Trade Organization, he warned.

This could include chlorinated chicken and hormone-treated beef if the UK fails to strike a deal with the US.