U.S. President Donald Trump will press Russian leader Vladimir Putin on Moscow's denial of meddling in the 2016 presidential election when the two leaders meet next month, national security adviser John Bolton said on Sunday.

Bolton said he discussed concerns about Russian meddling in the U.S. elections with Putin during his visit to Moscow on Wednesday, citing activities targeting congressional elections coming up in November as well as the 2016 presidential contest.

"The election meddling issue was definitely something we talked about," Bolton told the CBS "Face the Nation" program. Bolton said he brought up both the 2016 election and Russian activities in upcoming congressional elections.