Leaked documents purport to show Yahoo lobbying Brussels for different rules for "pseudonymous" data that would not afford it the same level of protection that non-anonymous information enjoys.
Pseudonymous data is information about people that does not directly identify them, but can be used by advertisers to target products and services at them.
In the document, Yahoo is said to want the EU to include a section in its Data Protection Regulations outlining different types of data and which rules apply to them.
At Yahoo we take privacy very seriously and have consistently prioritised transparency.
The draft laws are currently being debated by Brussels and Yahoo reportedly wants an alteration so that "in the context of pseudonymous data, legitimate interests rather than contract or explicit consent is the best-adapted legal basis for processing of this class of data."
An alternative recommendation would be the introduction of a sub-article establishing lawfulness where "processing is undertaken using data that are not identifiable to a person, or are rendered anonymous in such a way that the data subject is no longer identifiable by the data controller, accounting for all means likely reasonably to be used by the controller to identify the individual," the document states.
In a statement, Yahoo said: "At Yahoo we take privacy very seriously and have consistently prioritised transparency and choice for users on our website."
The European Digital Rights Group said the European Parliament had adopted a badly drafted opinion on data protection.
"The effect of the adopted text would be to effectively rip up decades of privacy legislation in Europe, undermining trust and confidence to the detriment of both citizens and business," the group said.
But Joe McNamee, executive director of the European Digital Rights Group, said there were positives to be drawn out of this result.
"The majority was not huge and the number of bad amendments was reduced over the past few days, in order to scrape this majority together. It is becoming increasingly difficult in the Parliament to find majorities for measures which are destructive to citizens' rights," he said.
