Ipsos Mori has denied that it offered to sell personally identifiable information from the call and text data of 27 million EE mobile network customers, but does not deny offering to sell anonymised information.
The research firm said it "absolutely refutes" accusations in the Sunday Times, which claimed that it had been offering EE call and text data to the police, as well as boasting that the data it had collated could be used to track individuals and their locations in and around 100 metres.
It is thought the police may have had an interest in the offer but backed out of the deal once it became public. The Metropolitan Police confirmed to the Sunday Times it had spoken with Ipsos Mori.
Ipsos Mori did not deny it was offering information full stop, instead assuring EE customers that any data was thoroughly anonymised.
In a statement, Ipsos Mori said it "absolutely refuted the suggestion that it [was] offering access to individual personal data for sale".
Instead it said its mobile analytics explored user volume, demographics and mobile web use from anonymised and aggregated groups of people.
"In conducting this research we only receive anonymised data without any personally identifiable information.
"We have taken every care to ensure it is being carried out in compliance with all relevant legal and regulatory requirements, including the Data Protection Act and Privacy and Electronic Communications (EC Directive) Regulations (both as amended)," it added.
As a result it said it could assure customers that it only received anonymised data without any personally identifiable information on any individual customers. The statement did not reveal exactly which demographics were up for sale.
"We do not have access to any names, personal address information, nor postcodes or phone numbers," it said.