An investigation has been launched into how personal data is being collected and used for targeting voters in political campaigns on social media, the UK's Information Commissioner's Office (ICO) has confirmed.
Elizabeth Denham, the Information Commissioner said that the official inquiry came amid rising concerns that big data was being collected and manipulated in unscrutinised ways.
The body had already launched an investigation into how the shadowy practices were used during the Brexit referendum, but said it was extending its scope for all political campaigns.
Announcing the probe via the ICO's website, Denham said: "Given the big data revolution, it is understandable that political campaigns are exploring the potential of advanced data analysis tools to help win votes.
"The public have the right to expect that this takes place in accordance with the law as it relates to data protection and electronic marketing.
"This is a complex and rapidly evolving area of activity and the level of awareness among the public about how data analytics works, and how their personal data is collected, shared and used through such tools, is low.
"What is clear is that these tools have a significant potential impact on individuals' privacy. It is important that there is greater and genuine transparency about the use of such techniques to ensure that people have control over their own data and the law is upheld."
The ICO's announcement comes days after the Electoral Commission also said it would review campaign financing laws as it emerged that parties were able to targeted Facebook adverts to bypass local spending checks.
In April, Facebook itself said it was aware that its platform was being manipulated to outcome the results of elections.
"Shining a light on such practices will require detailed investigative work and engagement with a range of organisations – political parties and campaigns, data companies and social media platforms, as well as international cooperation," Denham added.
"This investigation is a high priority for my office in our work to uphold the rights of individuals and ensure that political campaigners and companies providing services to political parties operate within UK law.
"We will provide an update later in the year."