Former National Security Agen­cy contractor Edward Snowden used log-in credentials and passwords provided unwittingly by colleagues at a base in Hawaii to access some of the classified material he leaked to the media, sources said.

A handful of agency employees who gave their log-in details to Snowden were identified, questioned and removed from their assignments, said a person close to several federal investigations into damage caused by the leaks.

Snowden may have persuaded 20 to 25 co-workers at the NSA regional operations center in Hawaii to give him their user names and passwords by telling them they were needed for him to do his job as a computer systems administrator, a second person said.

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 super-secret spy 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.

It is not clear what rules the workers broke by giving Snowden their passwords, which gave the contractor access to data that he was not authorized to see.

Snowden worked at the Hawaii site for about a month this past spring, during which he got access to and downloaded tens of thousands of secret NSA documents.

“In the classified world, there is a sharp distinction between insiders and outsiders. If you’ve been cleared and especially if you’ve been polygraphed, you’re an insider and you are presumed to be trustworthy,” said Steven Aftergood, a secrecy expert with the Federation of American Scientists.

Officials with the NSA and the Office of the Director of National Intelligence declined to comment because of a criminal investigation related to Snowden, who has been granted temporary asylum in Russia.

People familiar with efforts to assess the damage to U.S. intelligence caused by Snowden’s leaks have said assessments are proceeding slowly because Snowden succeeded in obscuring some electronic traces of how he accessed NSA records.

The sources did not know whether the NSA employees removed from their assignments were given other duties or fired.

— Reuters