(CNN) More than a million supporters of Edward Snowden have petitioned President Barack Obama to pardon him, but the former National Security Agency contractor hasn't submitted the required documents for clemency, according to the White House.

"Mr. Snowden has not filed paperwork to seek clemency from this administration," White House Press Secretary Josh Earnest said on Tuesday.

Snowden has remained in Russia since 2013, when he provided details of previously unknown domestic and international US surveillance programs to media outlets.

A number of high-profile human-rights groups have publicly requested Obama issue some type of clemency for Snowden, including the American Civil Liberties Union, Amnesty International and Human Rights Watch. They've argued that doing so would help other whistleblowers come forward with perceived government wrongdoing.

The White House has said consistently that Snowden's disclosures harmed national security, and insisted that returning to the United States for trail would be a necessary precursor to any pardon.

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