The charity Friends of the Earth is urging Michael Gove to commit to environmental protections before the UK leaves the EU.
Earlier in January, the environment secretary warned the farming community that a no deal Brexit could cause upheaval, because of extra trade tariffs and inspections to ensure food quality.
He also said that if new bills on food standards and animal welfare were introduced once the UK was not governed by the EU, they would have to pass through parliament first.
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But Craig Bennett of Friends of the Earth says Mr Gove should bring in any new legislation needed before the UK leaves the EU, not after.
“We’re concerned about how the environment is likely to get pushed even further down in the list of policies in the event of a no deal Brexit,” he told talkRADIO’s Matthew Wright.
“If we end up with a chaotic no deal, the focus is going to be on the economy and trade, and the idea that they’re going to make loads of time to bring in new environmental laws is cloud cuckoo land.”
'No one voted for a worse environment'
He pointed out that it was EU directives that stopped the UK pumping raw sewage straight into the sea.
“Everyone that voted leave or remain, no one voted for a worse off environment,” said Mr Bennett.
“Surely everyone can agree we need to put these measures in place before we leave, not after.
“Our past performance of successive UK governments has not been very good on this. In the 1990s, it was only after EU legislation that we finally stopped pumping raw sewage into the sea. I think we could well end up doing it again. Let’s push this up the agenda in this Brexit debate - we have to get environmental protections in place before we leave.”