United States President Donald Trump had another, previously undisclosed, conversation with Russian President Vladimir Putin at the G20 summit in Germany earlier this month.

The conversation came hours after Trump and Putin's first official face-to-face meeting on July 7, which was originally scheduled to last just half an hour but stretched on for more than two.

White House Spokesman Sean Spicer and National Security Council Spokesman Michael Anton confirmed that Trump and Putin spoke at a dinner for world leaders and their spouses at the Group of 20 summit in Hamburg, Germany.

The two world leaders were also captured on video shaking hands and exchanging a few words after they arrived at the G20 summit of industrialised and developing nations earlier that day.

Anton, however, would not specify the duration of the conversation.

During their first meeting, that lasted two hours and 16 minutes, Trump and Putin had a “robust and lengthy” discussion about the interference, though Putin denied involvement, Secretary of State Rex Tillerson said.