Google is facing concerns from EU officials over the length of time it stores users' search habits.
A working party of data protection officials from members states last week sent a letter to the search giant demanding justification for its policy of keeping hold of users' identity and search patterns for up to two years.
The FT reports the group questioned whether Google had "fulfilled all the necessary requirements" surrounding data retention legislation.
The search site recently launched a feature that gives access to search histories for users who offer permission. But Google also keeps search terms, IP addresses and other data from users who do not enable the tracking feature.
The site had introduced the two-year time limit in March after previously operating a policy of indefinite data retention, but the EU officials reportedly believe even this is too long, while Norway's Data Inspectorate has started its own investigation into search sites' policies.