Ministers have ordered an urgent search of their offices and the speaker of the House of Commons has opened a security review of parliament after last week’s leak of CCTV footage of former health secretary Matt Hancock.

Hancock resigned on Saturday night after the release of a video of him kissing Gina Coladangelo, who was his adviser in the health department.

Colleagues of Hancock said they had been shocked to realise their activities had been filmed in his private office, although ministers insisted on Monday that the ceiling-mounted camera was not “covert”.

“I feel quite sick,” said one. “This raises nerve-racking questions and I’m sure a lot of other ministers must be worried . . . sensitive discussions involving national security have taken place in that room.”

Steve Brine, a former health minister, said no one knew meetings were being recorded: “The issue to my mind is . . . more who had access to those images?”

An inquiry by the health department has begun into who originally introduced the CCTV camera in the health secretary’s private office at least four years ago.

A photograph from 2017 shows the same camera in the same place on the ceiling, soon after the department moved into its current premises in Victoria Street in central London.

The findings about the origins of the camera, which has now been switched off and taped up, will not be made public.

Government officials said privately they believe the images were leaked after someone who worked in the department contacted an anti-lockdown campaigner to try to place them in the media in return for a fee.

Emcor, the US company that provides security for the health department, has refused to answer detailed questions. According to analysis by Tussell, Emcor has secured 19 UK government contracts, including with councils and the NHS, worth £171m since 2010.

Peter Bone, a backbench Tory MP, said there was an apparent breach of the “Wilson Doctrine”, under which MPs are not allowed to be bugged by the authorities.

Robert Buckland, justice secretary, said CCTV was a fact of daily life but there was a “wider issue of concern” that inappropriate coverage could be used by hostile governments. He said his own department’s security team had carried out a search over the weekend for any cameras or listening devices but found none.

Julia Lopez, a Cabinet Office minister, said the video had not come from a “covert device” but admitted there were “obvious questions” about the vetting process for civil servants.

The cameras used in the health department’s building are produced by Chinese company Hikvision. The US government has banned American companies exporting products to Hikvision over concerns about their involvement in the repression of Uygur Muslims in Xinjiang.

The China Research Group of Tory MPs said Chinese state-backed surveillance technology was in various government buildings and called for a “central review of surveillance tech to assess security risks.”

Lopez said there were regular sweeps of more sensitive departments to look for illicit recording devices.

But Philip Ingram, a retired military intelligence and security officer, said that the leak of camera footage from Hancock’s office — together with the discovery of classified Ministry of Defence documents at a bus stop over the weekend — should prompt the government to tighten its grip on security. “Now is the time for Whitehall to shake itself up and show it’s taking security matters seriously,” he said.

Meanwhile, Jon Ashworth, shadow health secretary, called on Downing Street to sack Lord James Bethell, a junior health minister, following reports that both he and Hancock had used their private Gmail accounts to for government business.

Documents leaked to the Sunday Times showed a senior official warning that Hancock “corresponds only with private office via Gmail account”. Ashworth said Bethell should be sacked for using his personal email “to discuss government contracts”.

Elizabeth Denham, the Information Commissioner, said she was examining the revelations.

Angela Rayner, Labour’s deputy leader, called for a wider public inquiry into the practice — saying it could potentially breach the Official Secrets, Freedom of Information, Data Protection and Public Records acts.

Lopez said contracts had all gone through a formal “eight-stage process” regardless of how entrepreneurs initially approached the government.

Prime minister Boris Johnson refused to comment on Monday on whether he too had used his personal email address for state work.

A Department of Health and Social Care spokesperson said: “All ministers are aware of the rules around personal email usage and government business is conducted in line with those rules.”