Former US National Security Agency contractor Edward Snowden told the European Parliament that he alerted more than 10 officials to his concerns about US government snooping programmes before leaking documents about the efforts.
He wrote that he reported policy or legal issues related to spying programmes, but that his warnings fell on deaf ears. As a contractor, Snowden said, he had no legal avenue to pursue further whistle-blowing.
"Yes. I had reported these clearly problematic programmes to more than 10 distinct officials, none of whom took any action to address them," he said in written testimony.
"As an employee of a private company rather than a direct employee of the US government, I was not protected by US whistle-blower laws, and I would not have been protected from retaliation and legal sanction for revealing classified information about law-breaking in accordance with the recommended process."
Snowden worked for the CIA before becoming an NSA contractor for various companies. He was working at an NSA facility in Hawaii when he leaked information about government programmes to the media.
In August, US President Barack Obama said there were "other avenues" available to someone like Snowden "whose conscience was stirred and thought they needed to question government actions". Obama pointed to a system for questioning classified government actions under the Office of the Director of National Intelligence.
Elsewhere in his testimony, Snowden described the reaction he received when relating his concerns to co-workers and superiors. Some gave "well-meaning but hushed warnings not to 'rock the boat', for fear of the sort of retaliation that befell former NSA whistle-blowers", he wrote.
"Everyone in the intelligence community is aware of what happens to people who report concerns about unlawful but authorised operations," he said.
Snowden has claimed that he brought up issues with what he considers unlawful government programmes before.
The NSA disputes his account, previously saying that after an investigation it found no evidence to support Snowden's claim that he brought the matters to anyone's attention.
Both Obama and his national security adviser, Susan Rice, have said that Snowden should return to the United States and face criminal sanctions for his actions.
Snowden was charged with three felonies over the summer and has been living in Russia since fleeing the United States in the wake of the leaks.