Sinn Fein's Northern Ireland MEP has claimed to have obtained secret Civil Service documents outlining "the disastrous consequences" Brexit will have on Northern Ireland.
Martina Anderson called on the Civil Service to release the documents to the public.
The assessments looked at the border, the customs union and single market, and the availability of labour for key sectors such as health, agri-food and manufacturing post-Brexit. No further details of the assessments have been published.
"I have met the interim head of the Civil Service and directly challenged him to release all assessments publicly so people can see the full extent of the outworking of Brexit," she said.
"Despite initial Civil Service claims that it had no assessments, we have now received more than 30 papers on the impact of Brexit which it had shared with the British government."
Ms Anderson said the information had to be "dragged" out of the Civil Service. She added: "It paints a bleak picture and shows that Brexit will have a hugely detrimental impact on these key sectors, jeopardising future growth and potentially creating a real crisis in our health service.
"If the Civil Service had this information, it begs the question of what other information on Brexit it has and is not releasing. I am reiterating my call for all assessments on the impact of Brexit held by the Civil Service to be made public immediately so the public are fully aware of it."
Analysis published by the UK government in February said the Northern Ireland economy would take a 12% hit if there is no Brexit deal. The figures suggest that if a trade deal is agreed the Northern Ireland economy would take an 8% hit. In the event of a so-called soft Brexit, in which the UK would participate in the single market, the Northern Ireland economy would take a 2.5% hit.
The Executive Office did not comment on Ms Anderson's claim last night.