More than half of the memos former FBI chief James Comey wrote as personal recollections of his conversations with President Trump about the Russia investigation have been determined to contain classified information, according to interviews with officials familiar with the documents.

This revelation raises the possibility that Comey broke his own agency’s rules and ignored the same security protocol that he publicly criticized Hillary Clinton for in the waning days of the 2016 presidential election.

Comey testified last month he considered the memos to be personal documents and that he shared at least one of them with a Columbia University lawyer friend.