In his first remarks since WikiLeaks began releasing thousands of his hacked emails, John D. Podesta, Hillary Clinton’s campaign chairman, said Tuesday that Russian intelligence officials intent on swaying the election to Donald J. Trump had been responsible for the illegal breach into his account.

“I’ve been involved in politics for nearly five decades,” Mr. Podesta told reporters aboard the Clinton campaign plane. “This definitely is the first campaign that I’ve been involved with in which I’ve had to tangle with Russian intelligence agencies,” he added, “who seem to be doing everything that they can on behalf of our opponent.”

Without verifying the authenticity of the emails, Mr. Podesta said that he had spoken with the F.B.I. “as a victim” of hacking. The Obama administration, like Mr. Podesta, believes the Russian government has been trying to help Mr. Trump with its hacking, including the theft of emails of the Democratic National Committee this year.