Former Trump campaign adviser Roger Stone privately sought information he considered damaging to Hillary Clinton from WikiLeaks founder Julian Assange during the 2016 presidential campaign, according to emails reviewed by The Wall Street Journal.

The emails could raise new questions about Mr. Stone’s testimony before the House Intelligence Committee in September, in which he said he “merely wanted confirmation” from an acquaintance that Mr. Assange had information about Mrs. Clinton, according to a portion of the transcript...