Hillary Clinton went against the advice of security experts by continuing to use an unsecured BlackBerry smartphone while serving as secretary of state, new documents reveal.

Clinton was made aware that "unclassified BlackBerry is highly vulnerable in any setting," but nevertheless persisted in using her phone, Judicial Watch reported Thursday. The conservative watchdog group obtained an email in which Clinton spoke openly about retaining her phone contrary to counsel.

"Against the advice of the security hawks, I still do carry my berry but am prohibited from using it in my office, where I spend most of my time when I'm not on a plane or in a ‘no coverage' country," Clinton wrote in an email.

Judicial Watch submitted the email record as evidence to the U.S. District Court. The organization obtained the record through a court order as part of the ongoing case Judicial Watch, Inc. v. Department of State.

Judicial Watch has now counted 433 pertinent emails that Clinton did not provide to the State Department. Clinton had said in sworn declaration that she believed that she had turned over all emails that could have been "federal records."

"Mrs. Clinton seemingly ignored the advice of ‘security hawks' and violated numerous laws related to the handling of classified material and government documents," said Tom Fitton, president of Judicial Watch. "The State Department sat on this document for 18 months. It is a smoking gun that shows why she must be held accountable under criminal and civil law."

Clinton's personal "clintonemail.com" system was at the center of the FBI investigation into her potential mishandling of classified information. Judicial Watch has submitted an interrogatory into why she continued using a BlackBerry phone after she was advised not to do so.