The UK’s Information Commissioner Elizabeth Denham says she will seek a warrant to look at the databases and servers used by British data analytics firm Cambridge Analytica.
The firm is accused of using the personal data of 50 million Facebook members, amassed via a personality quiz app created by an academic.
Former employee Christopher Wylie claims the company used the data to influence the US presidential election.
The firm denies the allegations.
Ms Denham had demanded access to Cambridge Analytica’s servers by 18:00 GMT but said the firm had missed her deadline.
“I’m not accepting their response so therefore I’ll be applying to the court for a warrant,” she said.
“We need to get in there, we need to look at the databases, we need to look at the servers and understand how data was processed or deleted by Cambridge Analytica.”
Facebook has also announced that it has hired its own digital forensic team to audit Cambridge Analytica.
Cambridge Analytica insists that it followed the correct procedures.
“This is part of a comprehensive internal and external review that we are conducting to determine the accuracy of the claims that the Facebook data in question still exists,” Facebook said.
“If this data still exists, it would be a grave violation of Facebook’s policies and an unacceptable violation of trust and the commitments these groups made.”
Facebook added that Aleksandr Kogan, the creator of the personality app from which the Facebook data had been harvested, had also agreed to be audited.
However, Mr Wylie, who made the claims about the way the data was gathered and used, had declined.
On Monday, Cambridge Analytica was the focus of Channel 4 News report in which an undercover reporter met the company’s executives.
The reporter posed as a Sri Lankan businessman seeking to discredit a political rival.
In the film, chief executive Alexander Nix was filmed giving examples of how his firm could arrange for it to happen.
Mr Nix told the BBC’s Newsnight programme that he regarded the report as a “misrepresentation of the facts” and said he felt the firm had been “deliberately entrapped”.