A coalition of European and US consumer advocacy groups made a last-ditch appeal to Internet search and advertising giant Google on Wednesday to delay changes to its privacy policies.

In a joint letter to Google chief executive Larry Page, the Trans Atlantic Consumer Dialogue (TACD) urged Google to delay implementation of the changes which are scheduled to take effect from Thursday.

“On March 1, you propose to combine data from all of your services, provided by your users in very different contexts and for very different reasons, into a single profile without user consent and without any meaningful opportunity for users to opt-out,” the TACD letter said.