Photo: Al Drago/The New York Times; Video: By THE ASSOCIATED PRESS

Mr. Comey refused to answer a question from the committee chairman about whether the investigation the bureau conducted extended to the Clinton Foundation, which has faced questions about donations from foreign officials seeking to influence American policy.

“I’m not going to comment on the existence or nonexistence of other investigations,” he said.

“Was the Clinton Foundation tied into this investigation?” Mr. Chaffetz asked.

“I’m not going to answer that,” Mr. Comey said.