Michael McFaul, former U.S. ambassador to Russia in the Obama administration, said Tuesday that President Trump's second undisclosed conversation with Russian President Vladimir Putin could have been recorded.

McFaul said a Russian translator who observed the private interaction between Putin and Trump at the G-20 Summit in Hamburg, Germany, may have recorded what they said.

"It could have been recorded of course by the translator," McFaul said on MSNBC Tuesday night.

McFaul also speculated Putin may have taken notes of the conversation.

"President Putin is also pretty good at remembering these meetings, writing down notes, making notes afterwards," he said. "I most certainly believe that he would have done so."

Multiple news outlets reported Tuesday that Trump and Putin spoke in July at the end of a couples dinner in the main room of the G-20 summit where dinner was held following their two-hour long bilateral meeting earlier that day.

The White House did not previously disclose the second interaction, and has not detailed what Trump and Putin discussed.

McFaul said he is concerned there is no official account of the conversation.

"He [Putin] is trying to persuade Trump to be his buddy against the so-called fake news, against the deep state that is out to get him and Putin, and to bring him along to see the world the way he does, and he's very good at it," McFaul said. "So it troubles me that we don't know what they actually talked about."

A White House official told reporters there was nothing unusual about the conversation and Trump ridiculed press accounts of the interaction as "sick."

The first, bilateral meeting was the first face-to-face encounter between Trump and Putin.

In that meeting, in which Secretary of State Rex Tillerson and Russian Foreign Minister Sergey Lavrov were also present, Trump and Putin discussed Russia's election interference, and the ongoing Syrian war. It was originally scheduled to take place for half an hour, but ended up taking up two hours and 15 minutes.