Prince Mohammed s presence at the global summit has been contentious following the killing of Saudi journalist Jamal Khashoggi at a Saudi consulate in Istanbul in October.
The Saudi government has admitted that its officials were responsible for the murder of Khashoggi, who was a USA resident and a columnist for The Washington Post, but Saudi Arabia claims that the crown prince was not responsible.
This came after a high five between the man known as MBS and a grinning President Putin before the pair sat next to each other at the G20 conference.
The prince was also seen chatting with President Donald Trump and his daughter Ivanka, although in a nod to United States domestic outrage over Saudi Arabia, the White House downplayed the encounter.
Mrs May's appointment with...
Bolton's reluctance to hear the recording mirrored President Donald Trump's position that there is no need for him to listen.
Russian Federation and Saudi Arabia, the two countries which are heavyweights in oil production, are known to have close ties.
"It is absolutely the case that the relationship we have with Saudi Arabia means that we are able to raise issues that are hard issues", Ms May told reporters after the G20 summit concluded.
While Saudi officials have insisted the crown prince had no knowledge of the plan to kill Khashoggi, the Central Intelligence Agency reportedly concluded last month that the crown prince ordered the murder.
Watch what happened when Saudi Prince and Vladimir Putin met. Later in the one-minute clip posted on Twitter Macron says: "You never listen to me", and Mohammed bin Salman replies: "I will listen, of course".
Trump canceled his meeting with Putin on Thursday, citing clashes with Russian and Ukrainian military vessels.
Meanwhile, bin Salman talked with world leaders as accusations swirled about the gruesome killing of Khashoggi, who was tortured before he died.
"They exchanged pleasantries at the leaders' session as he did with almost every leader in attendance", a senior White House official said.
Both leaders are in Buenos Aires to attend the G20 summit on Friday and Saturday.
The killing has strained Saudi Arabia's ties with the West and battered Prince Mohammed's image overseas. He also pushed the issue of imprisoned human rights workers and the "humanitarian catastrophe" from violence in Yemen.