A banner showing pictures of (L-R) North Korean leader Kim Jong Un, South Korean President Moon Jae-in and US President Donald Trump in Seoul, on June 29. Jung Yeon-je/AFP/Getty Images

South Korean President Moon Jae-in has been one of the most enthusiastic proponents for peace between the US and North Korea.

He is currently attending the G20 alongside other world leaders, including US President Donald Trump, who earlier today tweeted out an invitation to North Korea's Kim Jong Un to meet him in the demilitarized zone that separates the two Koreas.

It's not known whether Moon was aware of Trump's invitation before it was issued, but the South Korean Blue House confirmed that Trump had brought it up with Moon on Saturday morning.

Walking up to Moon in the G20 coffee lounge, Trump asked, "Have you seen my tweet?"

Moon said, "Yes." According to the Blue House, Trump then gave Moon a thumbs-up and said "Let's try together."

North Korea said in a statement on state media KCNA that it had seen the tweet but had not received an official proposal.