WASHINGTON — Hillary Clinton forwarded a chain of emails in 2009 to her daughter, Chelsea, that included information, most likely about climate talks, that the State Department later declared to be classified, according to a new batch of emails released on Friday.

The email chain was among thousands of messages that the F.B.I. uncovered as part of its yearlong investigation into Mrs. Clinton’s handling of classified information on the private email server she used while secretary of state.

The State Department had previously released parts of the chain — which involved senior members of the White House, Treasury Department and State Department — with the information entirely redacted. The disclosure on Friday appeared to be the first to show that Mrs. Clinton had forwarded information of a delicate nature to her daughter, who had an email address on her server under a pseudonym.

The chain, among 285 pages of emails released by the State Department on Friday, renewed attention on Mrs. Clinton’s handling of classified material, an issue that has dogged her campaign from its inception and has given fodder to her Republican rival, Donald J. Trump. The F.B.I. reignited the issue last Friday when its director, James B. Comey, informed Congress that investigators had uncovered additional emails to and from a close Clinton aide, Huma Abedin, on the computer of her estranged husband, Anthony D. Weiner.