Even behind bars, Bernard Kerik is able to tell the world he’s against a planned Ground Zero mosque, thanks to Twitter.

The disgraced former police commissioner tweeted a link to a one-minute video that denounces the plan to build a 13-story mosque and community center near the Twin Towers site, according to Salon.com.

The ad claims that radical Muslims want the mosque to “validate their sense of victory on 9/11” and that its construction would “encourage future attacks on America.”

Prison officials weren’t sure how Kerik tweeted, since inmates aren’t allowed access to the Internet or Twitter. They speculated that Kerik may have sent an e-mail to a family member through a program that prisoners are allowed to use and that the family member tweeted in Kerik’s name.

Kerik pleaded guilty last November to charges that included tax fraud and lying to White House officials and is not due to be released from a minimum-security federal prison in Cumberland, Md., until July 30, 2013.