Michael Gove has been warned not to let Brexit preparations get in the way of work to protect the environment.
Some 400 staff have been loaned or seconded to the Department for Environment, Food and Rural Affairs from its agencies.
Environment secretary Gove insisted that “priority roles” in bodies including Natural England (NE) and the Environment Agency were being “backfilled” if staff had left to work on Brexit.
But Mary Creagh, chairwoman of the Commons Environmental Audit Committee said it was “disappointing” that NE had been “raided” for staff.
Around 50 staff from NE have been seconded to Brexit roles.
Of those, 13 had been spending most of their time working on sites of specific scientific interest (SSSIs).
In a letter to Creagh, Gove said: “The work that people were doing on SSSIs prior to their EU Exit secondments has been passed to others to absorb in to their workplans.”
Concerns have been raised about SSSIs after figures from Natural England showed a fall over the last two years in the proportion of SSSIs assessed as being in a favourable condition.
Creagh said: “Preparations for leaving the EU must not get in the way of protecting our treasured natural spaces and iconic British wildlife.
“It is disappointing that Defra has raided staff at Natural England, the organisation responsible for protecting some of the most highly valued wildlife areas in England to prepare for Brexit.
“Natural England must not become a poor relation to Defra. Ministers must ensure the valuable work it does to promote biodiversity is given the priority it deserves.”
Green Party MP Caroline Lucas said: “The Government’s poaching of Natural England staff for Brexit work is the latest in a string of cutbacks that are decimating the agency that looks after irreplaceable habitats and beautiful landscapes.
“This letter proves Michael Gove’s promise of a ‘Green Brexit’ is pure bluster.”