Hillary Clinton deflected responsibility Friday for what the FBI called her careless handling of sensitive government secrets, saying that officials with whom she corresponded as secretary of state did not treat the information as secret.

In her first remarks about FBI findings that were highly critical of her stewardship of classified information, Clinton said she made a mistake in setting up the privately owned email system she used when she was secretary of state. But she repeatedly noted that information later identified as classified was part of correspondence with hundreds of government officials who did not flag any problem.

“I believe and have said many times that I take classified material seriously,” Clinton said in an interview with NBC. “I dealt with over 300 people in the State Department, many with decades of experience, who understand clearly how to handle classified material.”

In most but not all cases investigated by the FBI, others initiated communications with content that was later identified as sensitive. Those messages were sent directly or forwarded to Clinton.

The references to other government officials, repeated in other interviews Clinton conducted Friday, represent a new line of defense in the long public debate over an issue that has led many voters to say they do not trust her.

“I do not believe that all of the professionals that I dealt with in the State Department were careless in handling classified material,” Clinton said. “I do not believe that they did anything that in any way, they believed, was inappropriate.”

Until now, Clinton had not discussed in any detail that the messages involved scores of other government officials with security clearances and knowledge of the handling of sensitive material.

Previously, Clinton had said she never knowingly sent any classified information over her private email system. FBI Director James B. Comey did not contradict that assertion in announcing his findings this week but did say in House testimony that she had been negligent.

“I think he’s clarified it. The State Department has clarified it,” Clinton said. “I have said, I regret using a personal email.”

[House Republicans grill FBI’s Comey on Clinton emails]

Comey presided over a year-long investigation that found Clinton’s setup to be problematic, but he said Tuesday that the matter should be closed with no criminal charges. The case was closed by the Justice Department the next day.

The State Department, however, said Thursday that it was reopening its internal review of the matter — which could potentially bring professional consequences for Clinton or her top aides there.

Clinton did not answer direct questions in a CNN interview about whether she would cooperate in the State Department inquiry.

The Republican National Committee said in an email to reporters that Clinton “continued to misrepresent the facts about her email scandal and refused to commit to cooperating with a rekindled State Department probe into her handling of classified material.”

Republicans have called on the Obama administration to deny her access to classified briefings.