A State Department spokesman could not say with certainty that former Secretary of State Hillary Clinton did not bring her personal BlackBerry phone into secured areas of the agency's headquarters.

In a deposition made public Thursday, former State Department executive secretary Lewis Lukens said he had witnessed Clinton using her BlackBerry in the hall outside her office on several occasions. Clinton's office is a classified environment, meaning no personal devices are allowed inside without a waiver.

"There was no waiver permitting their use ever granted during Secretary Clinton's tenure," State Department spokesman Mark Toner said Friday.

"It's a secure environment up there, and there are safes and other locks, areas where you need to stash your BlackBerry or your PDA before entering that environment," he added.

But Toner was not as confident that Clinton had followed those rules during her time at State.

"I have no reason to believe that that wasn't observed during her tenure," he said.

During his deposition, which was taken by the conservative group Judicial Watch, Lukens acknowledged that members of Clinton's staff were at one time searching for a "workaround" to allow Clinton to check her emails on the seventh floor of the building, where her office is located.

Lukens said Cheryl Mills, Clinton's chief of staff, had rejected the agency's offer to set up a computer for that purpose because Clinton only knew how to access her inbox on a BlackBerry.

Controversy over Clinton's decision to use a personal server for all her work-related communications was reignited this week when the State Department inspector general published the results of a year-long audit. That review highlighted, among other things, missing emails that described Clinton's refusal to set up an official account for fear that her messages could become "accessible."