Spy agencies decline to comment on whether their agents have gone rogue.
NSA and GCHQ agents have been regularly informing the Tor anonymity network of bugs in its code, according to its executive director Andrew Lewman.
He believes that anonymous reports received by the network are sent by spooks whose job is to find flaws in the project, which if true would undermine attempts by spy agencies to uncloak users.
Speaking to the BBC he said: "There are plenty of people in both organisations who can anonymously leak data to us to say – maybe you should look here, maybe you should look at this to fix this."
While he noted that he could not confirm the identity of the messengers, he had "a hunch" that the reports were coming from British and American cyber spies.
"You have to think about the type of people who would be able to do this and have the expertise and time to read Tor source code from scratch for hours, for weeks, for months, and find and elucidate these super subtle bugs or other things that they probably don’t get to see in most commercial software."
Both agencies declined to comment on the allegations, though the US Depart of Defence has previously denied that it collects personal data from Tor users.
The network claimed it had been attacked earlier this year, pointing the finger at researchers who recently pulled out of a talk on uncloaking Tor users at the Black Hat conference in Las Vegas.