Edward Snowden, the fugitive US intelligence leaker, did not gain access to the "crown jewels" of America's spy programmes that secretly intercept and monitor conversations globally, according to a media report.
The Obama administration is reviewing what the admitted leaker of classified information actually got his hands on and what damage he may have caused, CNN reported.
"The ongoing damage assessment indicates he did not gain access to what is called ECI or "extremely compartmentalised information," it quoted a US official familiar with the ongoing review as saying.
The assessment also has concluded that Snowden took advantage of knowing that a good deal of information was concentrated in one portion of the National Security Agency's (NSA) computer system.
"What he had was information that was centralised so it could be shared broadly," the official said.
The government believes Snowden was aware that upgrades were being made to NSA systems tagging data and users so that downloads were recorded, but he accessed portions where that work had not been completed.
Snowden had recently claimed that he had very sensitive "blueprints" detailing how the NSA operates that would allow someone who read them to evade or even duplicate NSA surveillance.
Snowden, 30, who was holed up at the Moscow airport for a month was today given a document by Russian migration service that allows him to leave the airport transit zone. He faces espionage charges in the US.
The former technical contractor and Central Intelligence Agency (CIA) employee worked for Booz Allen Hamilton, a contractor for the NSA in Hawaii.
The US official said the Obama administration believes it knows the extent of the material that was downloaded.
"We are not downplaying it," he said, explaining that assessing the matter over weeks has enabled authorities to focus more directly on the impact of Snowden's actions.
Officials do not dispute that Snowden had critical information about how NSA programmes worked.
"But just because you have the blueprints doesn't mean you have the manual," the official said.
A key question is whether Snowden really knows how the programmes work at a detailed technical level, he said.
Snowden had leaked sensitive documents about US anti- terror programmes, detailing secret telephone metadata and e- mail surveillance.
Meanwhile, following the Snowden incident, system administrators and others will be subject to more stringent rules, the report said.
Downloads will require a second more senior employee to "watch, log and observe" what material is being accessed the official said, adding that access codes and passwords also have been changed.
