Far more than 87 million people may have had their Facebook data harvested by Cambridge Analytica, according to evidence from former employee Brittany Kaiser.

Speaking to the Commons digital, culture, media and sport select committee, Kaiser said Cambridge Analytica had a suite of personality quizzes designed to extract personal data from the social network, of which Aleksandr Kogan’s This Is Your Digital Life app was just one example.

In evidence to the committee, Kaiser wrote: “The Kogan/GSR datasets and questionnaires were not the only Facebook-connected questionnaires and datasets which Cambridge Analytica used. I am aware in a general sense of a wide range of surveys which were done by CA or its partners, usually with a Facebook login – for example, the ‘sex compass’ quiz.

“I do not know the specifics of these surveys or how the data was acquired or processed. But I believe it is almost certain that the number of Facebook users whose data was compromised through routes similar to that used by Kogan is much greater than 87 million; and that both Cambridge Analytica and other unconnected companies and campaigns were involved in these activities.”

Giving oral evidence on Tuesday, Kaiser said: “When I first joined the company, our creative and psychology teams, and data science teams, would work together to design some of these questionnaires.

“In my pitches I used to give examples, even to clients, that if you go on Facebook and you see these viral personality quizzes, that not all of them would be designed by Cambridge Analytica, SCL group or our affiliates, but these applications were designed specifically to harvest data from individuals using Facebook as the tool.

“So I know, at least of those two examples, the music version and the sex compass, which were both quizzes that were separate from Aleksandr Kogan’s quiz. Therefore it can be inferred or implied that there were many additional individuals as opposed to just the ones through Aleksandr Kogan’s test whose may have been compromised.”

Facebook’s chief technology officer, Mike Schroepfer ,wrote in a blogpost earlier this month that as many as 87 million users may have had their data taken, higher than the previous estimate of 50 million.

Facebook told the Guardian: “We are currently investigating all apps that had access to large amounts of information before we changed our platform to dramatically reduce data access in 2014. We will conduct a full audit of any app with suspicious activity. And if we find developers that misused personally identifiable information, we will ban them and tell everyone affected.”

Kaiser also said she had “specific concerns of legality” about the working practices of Leave.EU, the unofficial pro-Brexit campaign founded by the insurance magnate Arron Banks.

She described Banks explicitly asking her if there could be savings on the work Cambridge Analytica was carrying out if the company could process data from Leave.EU, Ukip and Banks’ insurance company Eldon together.

“We were never commissioned to do this work,” Kaiser said. “But I do believe that this work was carried out, just not by Cambridge Analytica.”

Kaiser also described attending the headquarters of Leave.EU to supervise the organisation’s data collection team in order to ensure that the information they received through their phone banking operation was useful for the data analysis. When there, she said, she was surprised to discover that the people staffing the phones were employees of Eldon Insurance.

“In regards to this proposal and work that I believe was undertaken, with or without us, there’s a few specific concerns of legality,” Kaiser said. “Firstly it’s in relations to breaches of electoral law, for chargeable work, some of which I did which was never paid for, and unreported to the electoral commission.”

Kaiser alleged that Cambridge Analytica had carried out £41,500-worth of work for the Leave.EU campaign, which was billed to Ukip, but not paid for.

“Secondly, I have evidence from my own eyes of possible breaches of the Data Protection Act concerning the usage of personal and commercial data of individuals in the Eldon Insurance database and possibly the Ukip database, being used for the benefit of the Leave.EU campaign,” she said.