Former U.S. National Security Agency contractor, Edward Snowden, has censured WikiLeaks’ release of information without proper curation.

On Thursday, Snowden, who has embarrassed the U.S. government with revelations of widespread NSA surveillance, said that WikiLeaks was mistaken in not at least modestly curating the information it releases. “Democratizing information has never been more vital, and @Wikileaks has helped. But their hostility to even modest curation is a mistake,” Snowden said in a tweet.

WikiLeaks shot back at Snowden that “opportunism won’t earn you a pardon from Clinton & curation is not censorship of ruling party cash flows.”

The whistleblowing site appeared to defend itself earlier on Thursday while referring to its “accuracy policy.” In a Twitter message it said that it does “not tamper with the evidentiary value of important historical archives.”

Hillary Clinton accepted on Thursday her nomination as the candidate of the Democratic Party for president of the U.S. Snowden was granted asylum by Russia so that he could avoid prosecution in the U.S. for his revelations of confidential government information.

WikiLeaks recently released emails stolen from the Democratic National Committee, which suggested that committee officials had favored Clinton over rival Senator Bernie Sanders. There is speculation that the DNC was hacked by Russians aiming to influence the elections. WikiLeaks has refused to disclose its source.

On Thursday, Director of National Intelligence, James Clapper, said his agency was not quite ready yet to make a public call on the attribution of the hack.

WikiLeaks’ release of the emails, which contained sometimes information such as email ids, phone numbers and passport numbers of DNC donors has been criticized.

WikiLeaks was also criticized after its release of emails said to belong to Turkey’s ruling party, the AKP or Justice and Development Party. WikiLeaks also posted links on social media to databases that were said to contain sensitive and private information of millions of ordinary people, including a special database of almost all adult women in Turkey. It later turned out WikiLeaks had linked to a database uploaded by another person, which was disabled after the controversy.