Some of those seeking to scrub their histories from the web under Europe's "right to be forgotten" rule are being economical with the truth when making their requests, according to Google.

In a letter to European data regulators, Google listed some of the challenges it faces in complying with the ruling, which allows people to compel search engines like Google and Bing to remove links to pages that mention their name, if the references are "inadequate," "irrelevant" or "excessive".

Part of the problem is that Google must often rely on information submitted by the requester in granting or rejecting a request.

"Some requests turn out to have been made with false and inaccurate information," Google said. "Even if requesters provide us with accurate information, they understandably may avoid presenting facts that are not in their favour."

For example, it said, someone might want to remove an old article about crimes they committed when they were a teenager - without revealing they'd been convicted of similar crimes as an adult.

As a result, Google might not be aware of information that would support leaving the search result intact.

Google has criticised the ruling in the past but said it's working to comply with it nonetheless. Its letter last week was in response to a questionnaire from regulators seeking more details about how it handles the requests.

As of July 18, Google had received more than 91,000 requests involving more than 328,000 URLs. On July 31 it said it had removed around 53%, or just over half, of those URLs. It declined to remove about a third of them, and requested more information in 15% of cases. It said those percentages could shift over time.

Reasons it might not grant a request include if removing the link would not be in the public interest, or if the contents of a link involve political speech, it said.

People in France and Germany submitted the most requests, at 17,500 and 16,500, respectively, Google said, followed by the UK with 12,000 requests, Spain with 8,000, Italy with 7,500 and Holland with 5,500.

Some webmasters have complained to Google about the removal of links to their sites, it said.

Others besides Google have criticised the ruling. Last week a House of Lords subcommittee said the ruling was unworkable and misguided. It said it could be particularly damaging for smaller search engines that don't have the resources to handle the requests.

Google provides a form online for the removal requests. So does Microsoft's Bing.

"We continue to work out the details of the process we'll use to evaluate the requests," a Microsoft spokeswoman said.