(CNN) Attorney General Jeff Sessions met twice last year with the top Russian diplomat in Washington whose interactions with former Trump national security adviser Mike Flynn led to Flynn's firing, according to the Justice Department.

Sessions did not mention either meeting during his confirmation hearings when he said he knew of no contacts between Trump surrogates and Russians. A Justice official said Sessions didn't mislead senators during his confirmation.

The Washington Post first reported on Sessions' meetings with the official.

Sergey Kislyak, the Russian ambassador, is considered by US intelligence to be one of Russia's top spies and spy-recruiters in Washington, according to current and former senior US government officials.

Sessions met with Kislyak twice, in July on the sidelines of the Republican convention, and in September in his office when Sessions was a member of the Senate Armed Services committee. Sessions was an early Trump backer and regular surrogate for him as a candidate.

Kislyak's potential proximity to Russian spying is one reason why Flynn's interactions with him, and Flynn's failure to disclose what he discussed with Kislyak, raised concerns among intelligence officials.

Sessions' spokeswoman Sarah Isgur Flores said there was nothing "misleading about his answer" to Congress because the Alabama Republican "was asked during the hearing about communications between Russia and the Trump campaign -- not about meetings he took as a senator and a member of the Armed Services Committee."

"Last year, the Senator had over 25 conversations with foreign ambassadors as a senior member of the Armed Services Committee, including the British, Korean, Japanese, Polish, Indian, Chinese, Canadian, Australian, German and Russian ambassadors," Isgur Flores said in the statement.