(AP) — The State Department review of Hillary Rodham Clinton's emails so far has found as many as 305 messages that could contain classified information and require further scrutiny by federal agencies, the department said Monday.

In a court filing that was part of a lawsuit against the State Department, officials told a federal judge in Washington they would be able to meet an existing schedule to release copies of Clinton's emails because only about 5 percent of the messages reviewed so far contain possible secret information that could hold them back for further analysis. The agency said those 305 emails with potential classified data were among more than 1,500 documents analyzed so far.

The filing came after Clinton said in an Iowa radio interview that during her stint as secretary of state in the Obama administration, she had never sent or received any emails on her private server that had information clearly marked classified. Republican critics have warned that Clinton may have compromised national security by sending and receiving messages that contained secret information, but she has sloughed off the criticism, saying she followed security guidelines and is the one who made the previously withheld emails available to the American public.

"If I had not asked for my emails all to be made public, none of this would have been in the public arena," she said in the interview, recorded last Friday. But The Associated Press and other news organizations had sought copies of Clinton's emails under the U.S. Freedom of Information Act for years.