A "very dangerous shift" towards a "privatised version of Big Brother" is on the horizon if UK authorities don't wake up to the invasion of privacy by internet companies, an influential Tory MP has warned.

In a debate about Google and privacy hosted by the pressure group Big Brother Watch, Rob Halfon, who is the Conservative MP for Harlow, said he believed there are many cases of privacy invasion by internet companies yet to be uncovered, and that parliamentarians need to be much more alive to the issue.

Google is facing criminal investigations around the world – including in the UK – for its interception of personal data about home wireless networks, taken from the company's StreetView mapping cars. The search giant admitted to accidentally intercepting extracts of personal data in May.

"The problem with Google and other big internet companies is that, despite having produced great technological advances, they have forgotten that people are individuals too," Halfon told Tuesday's debate. "We're getting into a situation where – just as we're starting to get rid of the previous government's surveillance society – we're now replacing it with another one: dare I say it, a privatised kind of surveillance society."

Halfon pointed to allegations of companies "trawling Facebook looking for customers saying negative things … that's something worthy of the secret police. If this happened in Soviet Russia you could quite understand it."

While pointing out that he's not against private companies, the MP said more needs to be done to protect the individual: "I suspect there's a lot of privacy encroachment going on which is yet to be uncovered and that these are just a couple of stories we've just seen in the media. The reason I believe there should be an inquiry into the role of the internet and its relationship to individual liberty is because there is so much going on under the surface, tracking what we do on the internet, tracking what we say on the internet, all for commercial purposes.

"There's danger that no one will have any privacy whatsoever. And this time the threat is not from the state, it's actually private companies who have acquired the right to photograph what goes on in people's gardens. That is a very dangerous shift because we will be living, dare I say it, in a privatised version of Big Brother. That's the scenario slowly creeping up upon us."

The Metropolitan Police launched a criminal investigation into Google last month on the request of Privacy International, which alleges that the search company carried out "criminal interception of wireless communications content," constituting an offence under the Regulation of Investigatory Powers Act and the Wireless Telegraphy Act. Last month, Halfon put forward an early day motion formally requesting a House of Commons debate on "the new threat of a surveillance society".

So far, 24 MPs have signed Halfon's Commons motion, with the most prominent of them being the former shadow home secretary David Davis.

In May this year, the UK's information commissioner said he did not want to "declare war" on Google over its breach of the Data Protection Act by collecting data about home wireless networks - despite Germany, Spain, France and Italy all launching investigations under the same European legislation.

The commissioner's reaction was criticised by both Simon Davies, director of Privacy International, and Alex Deane, director of Big Brother Watch, Deane saying: "If an investigation is warranted to the criminal standard – I'm not saying anyone's guilty of anything so far – how can you possibly say our information commissioner should not have been looking into what was going on in this company?

"That's why I think our information commissioner has been asleep on the job, on that point. His international fellows have really put him to shame. We've got to make sure not only the people responsible for the technology are awake but also the watchdogs are awake."

Davies went further, saying the commissioner's office is "both spineless and gutless", adding: "That, unfortunately, has been the legacy of the office for a long time."

Sarah Hunter, Google's head of UK public policy, attended the event but was restricted in what she could say by ongoing legal proceedings. Hunter did say Google had taken on board privacy concerns that have arisen in the past six months and that concerns expressed at the debate would be relayed back to colleagues, adding: "The answer to a lot of these concerns is finding ways to give people control over their own personal data – that's got to be at the heart of solving this conundrum.

"I think Google, or any of the responsible internet companies, understand the concerns that are expressed - how could we not be? I don't think it's true to say Google top brass don't get this. I think the last six months have been a real … I think everyone's noted it, shall we say. I think we are very mindful of the challenges that the internet poses as a whole.

"At the heart of solving those challenges, we think, is giving people control over their data - giving people the capacity to both take their information away from the services, and to give people the real sense of what their information is being used for, because I don't think the internet as a platform works on an everyone-opting-in-on-every-service basis."