Former Russian ambassador to the U.S. Sergei Kislyak denied Saturday that he discussed state secrets, or the issue of U.S. sanctions on Russia, with Trump's now-ousted national security adviser Mike Flynn.

"I did not discuss sanctions with anyone, and rest assured that I carried out my instructions honestly," the former diplomat said. He added that he "does not bargain for sanctions," which he considers to be illegal.

Kislyak said the talks were entirely appropriate. "How can it be that a diplomat is forbidden to communicate with representatives of the elected administration? Any diplomat — Russian, not Russian — is working to better understand the policy of the country where he works," he said on Russian TV, according to a USA Today report.

Flynn was ousted from the Trump administration in February after it was reported that he misled the Trump administration about his communications with Kislyak, which U.S. officials believe touched on sanctions.

On Friday, the New York Times reported that special counsel Robert Mueller's team, which is investigating Russian interference in the 2016 election, has asked the White House for documents concerning Flynn, the first known instance of the investigation doing so.

Also this week, it was reported that Mueller has impaneled multiple grand juries in relation to his Russia probe.