Lawyers say they will issue judicial review proceedings if Brexit secretary fails to release 50 studies of effect on industry.

David Davis, the Brexit secretary, has been threatened with legal action over his refusal to publish 50 secret studies commissioned on the impact of Brexit.

Lawyers acting for the Good Law Project, which is bringing the action jointly with the Green party MEP Molly Scott Cato, wrote to the Brexit department and Treasury on Thursday demanding the release of the documents. They said that failure to do so within 14 days would result in the issue of judicial review proceedings before the high court in an attempt to force their release.

The 50 studies into the impact of Brexit on different industries were commissioned earlier this year but the government has argued that publishing them could damage the UK’s negotiating position with Brussels.

Jolyon Maugham QC, who runs the GLP, said he would not bring the case without believing it had “good, serious prospects” of succeeding. He said he had received legal advice that the government may have a duty under common law to publish the studies into the potential impact on jobs and living standards.

“It seems to me the government’s reluctance to release these studies is born not of its ability to damage our negotiating position but what’s politically expedient,” he said.

The GLP has launched a crowdfunding campaign to cover the costs of the judicial review proceedings. Maugham previously raised more than £300,000 to challenge the government’s position that article 50 could be triggered by royal prerogative, and £70,000 to launch the Dublin case to establish whether the article 50 notification could be revoked.

Scott Cato, who has made several unsuccessful attempts to force the government to release the studies, including freedom of information requests, said the rule of law required that MPs know “what Brexit really means before they formally vote for our withdrawal”.

“The European referendum was all about taking back control but how can our democratic representatives make decisions in our interests when the government is withholding vital information?” she said. “It has been clear for some time that the attempt to keep the Brexit impact studies secret is more to cover the government’s blushes than to enable efficient lawmaking.”

More than 120 MPs have signed a letter demanding that Davis publish the findings.

The letter, coordinated by Labour’s David Lammy and Seema Malhotra, accused the government of keeping “not only parliament but the public in the dark” and said failure to disclose the advice was preventing MPs from holding ministers to account.

The Department for Exiting the EU has refused even to confirm which sectors are covered by the impact assessments, but said the list of those industries would be published “shortly”.