Whitehall’s Brexit department has enforced seven “gagging orders” on outsourcing firms and suppliers working on no-deal preparations, despite Theresa May’s previous criticism of such contracts.

The disclosure comes as the Department for Environment, Food and Rural Affairs (Defra), run by Michael Gove, confirmed for the first time that it had also asked suppliers to sign non-disclosure agreements [NDAs] as it geared up for the possibility of the UK crashing out of Europe.

Six government departments have now admitted using NDAs on more than 62 partners working on no-deal preparations, preventing them from revealing any information related to contingency plans.

The latest disclosure comes as business leaders implore the government to lift the veil of secrecy surrounding the UK’s EU exit.

The details about the Department for Exiting the EU’s use of NDAs emerged from parliamentary questions asked by the Labour MP Rushanara Ali.

The DExEU junior minister Chris Heaton-Harris replied saying the department had seven NDAs with providers for “media monitoring, consultancy and research” and defended their use.

“The use of NDAs is limited to standard contractual arrangements with those providing services to support our work and are necessary to protect commercial considerations,” he said during no-deal discussions.

David Rutley, a Defra minister, has also confirmed the use of NDAs.

Ali said: “It is unacceptable that the government continues to pursue a policy of silencing businesses and industry from speaking out about the disastrous implications of a no-deal Brexit.

“Leaving the EU without a deal will cause irrevocable damage to the UK’s economy and people’s lives. The government must stop hiding the truth, and take no deal off the table immediately.”

The Guardian revealed in December that the Department of Health and Social Care (DHSC) had imposed 26 NDAs, which were signed by pharmaceutical organisations planning to maintain medical supplies in the event of no deal.

It also emerged last month that the Department for Transport has 28 NDAs in force, forbidding firms and organisations from discussing plans on managing haulage in Kent, the border and customs.

Official figures show DExEU has paid £4,049,995 for services from big firms such as McKinsey, KPMG and PwC since it was founded in 2016.

The department has been in turmoil because of a high staff turnover and is recruiting more analysts. One advert seeks seven analysts, on salaries between £49,000 and £70,000, who will “play a critical role” in analysis shaping decisions before the UK leaves the EU and in the negotiations after.

The prime minister has previously condemned the use of NDAs by employers. She told parliament in October that it was clear they were being used unethically.

Whitehall is being so secretive that information is only being provided to some firms orally, or via hard copies of documents that must be returned at the end of meetings.

The government has been in close contact with the pharmaceutical industry, which is stockpiling drugs to ensure access to vital medicines if supply routes are disrupted by delays at the border.

A template NDA, published by the DHSC in response to another written parliamentary question from Labour, says the government “will need to share confidential and sensitive information about customs and border arrangements and supply routes”.

People attending meetings with civil servants are required not to divulge what they have heard, “not to take or make a copy of any papers provided for a meeting”, and “to return at the end of each meeting where requested any papers or material provided by the department”.

