Reuters reports that whistle-blower Edward Snowden persuaded other NSA workers to give him their log-in credentials. The Guardian / Reuters

Former National Security Agency contractor Edward Snowden allegedly used logins and passwords provided unwittingly by colleagues at a base in Hawaii to access some of the classified material he leaked to the media, Reuters reported Friday, citing unnamed sources.

A handful of agency employees who gave their login details to Snowden were identified, questioned and removed from their assignments, according to a source close to several government investigations into the damage caused by the leaks.

Snowden may have persuaded 20 to 25 fellow workers at the NSA regional operations center in Hawaii to give him their logins and passwords by telling them they were needed for him to do his job as a computer systems administrator, a second source alleged.

The revelation is the latest to indicate that inadequate security measures at the NSA played a significant role in the worst breach of classified data in the supersecret eavesdropping agency's 61-year history.

Reuters reported last month that the NSA failed to install the most up-to-date anti-leak software at the Hawaii site before Snowden went to work there and downloaded highly classified documents belonging to the agency and its British counterpart, Government Communication Headquarters.

Glenn Greenwald, who worked for The Guardian newspaper and has been publishing the revelations provided by Snowden, expressed doubt about the allegations. "Now that anonymous officials disseminated these claims through Reuters, let's blindly assume they're true," he said sarcastically on his Twitter account. "And when did it become journalistically sound to report what 'may have' happened? Anything 'may have' happened."

If those accounts are true, it is not clear what rules, if any, the employees may have broken by giving Snowden their passwords, which allowed the contractor unauthorized access to data.

Snowden worked at the Hawaii site for about a month last spring, during which he downloaded tens of thousands of secret NSA documents.