On Saturday, the Observer published the account of a former worker at data firm Cambridge Analytica, who lifted the lid on the company’s relationship with Facebook. Christopher Wylie revealed how an academic, Aleksandr Kogan, had harvested data from users via a personality quiz on the social network and, through his company Global Science Research (GSR), had shared it with Cambridge Analytica. Since then, there have been more revelations about both firms and about the way consumers’ data is used.

What have the main developments been this week?

A linked investigation by undercover reporters at Channel 4 News revealed the head of Cambridge Analytica, Alexander Nix, boasting of using dirty tricks to swing elections. Speaking to someone who he believed wanted to use the firm for work in Sri Lanka, he talked about creating sex scandals and using fake news to swing votes.

The report was followed by revelations of its role in the US elections – a senior member of staff claimed the firm was behind the “defeat crooked Hillary” ad campaign – and of its parent company’s activities in Nigerian politics.

Former employees of Facebook have also been speaking out. Sandy Parakilas, the platform operations manager responsible for policing data breaches by third-party software developers between 2011 and 2012, told the Guardian that other companies had used the same terms as Cambridge Analytica to access users’ data. He said he had warned senior executives at the company that its lax approach to data protection risked a major breach.

What else do we know about Cambridge Analytica?

The company’s ownership has come under the spotlight. In the US, it is backed by the Mercer family, who threw their weight behind Donald Trump in his run for president. In the UK, the company is linked with SCL Group. The government says it no longer has any contracts with SCL, but that it has worked with it in the past, while both Labour and the Conservatives were in power.

It has emerged that SCL was given access to confidential documents when working for the Ministry of Defence. It was paid almost £200,000 for carrying out two separate projects.

SCL Group has a number of Conservative donors among its shareholders and directors – one told the Guardian he had refused a request to introduce the firm to the party.

How have politicians and regulators responded?

Politicians around the world have expressed their concerns about the revelations and declared their intention to scrutinise the companies involved.

In the UK, MPs on the digital, culture, media and sport committee have accused Facebook of misleading it in a previous evidence session and called for Mark Zuckerberg to appear before them to answer questions. They have also recalled Nix.

The information commissioner applied for a warrant to access information from Cambridge Analytica, although the application was adjourned until Friday.

In the US, the Federal Trade Commission consumer body is reported to have opened an investigation into whether Facebook violated a privacy agreement it had. The attorney general of New York and his counterparts in Massachusetts and New Jersey have also announced privacy inquiries.

In Australia, the country’s Information and Privacy Commission has demanded that Facebook provide information on whether any Australians were affected by the unauthorised use of profile data.

As news of the data-mining scandal spread, Israeli authorities announced on Thursday they had informed Facebook that the country’s privacy protection agency was investigating the social media giant for potentially violating the rights of Israelis.

The agency was also looking into “the possibility of other infringements of the privacy law”, it said in a statement released by the justice ministry. Under Israeli law, personal data can only be used with consent and for the purpose under which it was given.

What about the public?

In the US a Facebook user has filed a legal complaint against Facebook for its use of her data and is suing for damages. Lawyers have suggested that others may follow.

Away from court #DeleteFacebook movement has been growing, and has been joined by the founder of WhatsApp, who sold his app to Facebook for $19bn in 2014. Investors dumped shares in Facebook on Monday, and the sell-off has continued during the week.

What has Facebook said?

Initially, Facebook tried to prevent the Observer reporting Wylie’s claims. Then, shortly before publication it announced that it was suspending his account, and those of SCL, Cambridge Analytica and Kogan.

On Monday it said it had hired a digital forensics firm, Stroz Friedberg, to conduct “a comprehensive audit” of Cambridge Analytica, but there was no word from the site’s founder Zuckerberg.

On Wednesday, Facebook said it would be changing the way it shares data with third-party applications.

Finally breaking cover, Zuckerberg told CNN that he was sorry for the “breach of trust”. He wrote in a Facebook post: “We have a responsibility to protect your data, and if we can’t then we don’t deserve to serve you”.

What has Cambridge Analytica said?

It strongly denied Wylie’s claims, and said that it had deleted all of the Facebook data once it became aware of how it had been obtained. “This Facebook data was not used by Cambridge Analytica as part of the services it provided to the Donald Trump presidential campaign; personality targeted advertising was not carried out for this client either,” it said.

It also accused Channel 4 News of “entrapment and mischaracterisation”. It said its report was “edited and scripted to grossly misrepresent the nature of those conversations and how the company conducts its business”.

However, on Tuesday it announced that the board of the company had decided to suspend Nix while an independent investigation was carried out.

What happens to Nix now?

The statement only referred to Cambridge Analytica so it is unclear if he will retain his role at SCL Group, or other companies he is linked to.