On Thursday, Al Jazeera released a preview of an interview with former NSA contractor and whistle-blower Edward Snowden, in which he addressed some of his more high-profile critics -- namely, U.S. presidential candidates Hillary Clinton and Donald Trump.

Snowden, who has been called a "traitor," someone who has aided terrorists, and a "dangerous person" by critics in both major parties, commented on the Clinton email scandal.

"This is a problem because anyone who has the clearances that the secretary of state has, or the director of any top level agency has, knows how classified information should be handled," he said.

"If an ordinary worker at the state department or the Central Intelligence Agency [...] were sending details about the security of embassies, which is alleged to be in her email, meetings with private government officials, foreign government officials and the statements that were made to them in confidence over unclassified email systems, they would not only lose their jobs and lose their clearance, they would very likely face prosecution for it."

Snowden leaked classified information exposing NSA spying and data collection programs targeted at U.S. citizens, foreign leaders, and people in other countries in 2013. The Justice Department has charged him with multiple counts of violating the Espionage Act and theft of government property, so he is all too familiar with how the government usually responds in situations like this.

A FBI investigation is currently underway over Clinton's use of a personal email server while she was secretary of state, including what sensitive or classified information may have been shared. The Hill reported Thursday that an ex-aide who worked on the server will likely plead the Fifth instead of testifying before Congress.

During his interview, Snowden also brushed off comments from Donald Trump, who called him a "total traitor," and even used the word "execution" when discussing what actions should be taken against Snowden. Snowden said it is "very difficult to respond in a serious way to any statement" made by Trump.

The full Snowden interview will air on Al Jazeera English on Friday.