The story surfaced last week in The Financial Times, which reported that several major firms had thrown their weight behind the scheme to measure cross-platform viewing behaviour.

Nielsen vice chairman Susan Whiting told employees in a memo: “While our company policy is not to respond to speculation or future announcements, we have been in direct contact with many of our clients, including some cited in the original article.

“Much of what was reported by the Financial Times remains unclear, and many of our clients are themselves looking for answers to questions raised by the story. What is clear, however, is that three-screen measurement is at the centre of our strategy.”

Whiting (pictured) said Nielsen had spent more than one billion dollars developing ways to track audiences for TV, web and mobile media. Several of the firm’s largest clients have recently renewed multi-year contracts for these and other measurement services, she added.

*Editor’s note: Story has been updated following receipt of memo from Nielsen.