Silicon Valley companies like Facebook have been openly critical of the Obama administration for its surveillance practices. But that's apparently not enough for Facebook chief executive Mark Zuckerberg, who lashed out Thursday at Washington.

"When our engineers work tirelessly to improve security, we imagine we're protecting you against criminals," Zuckerberg wrote in a blog post, "not our own government."

Zuckerberg went on: "The U.S. government should be the champion for the Internet, not a threat. They need to be much more transparent about what they're doing, or otherwise people will believe the worst."

Zuckerberg has vented about the issue in phone calls to President Obama, the social network co-founder said. The full blog post is available below.