With a smirk and a finger point, United States President Donald Trump dryly told Russia's Vladimir Putin "don't meddle with the election" in their first meeting since the Mueller probe concluded that Russia extensively interfered with the 2016 campaign.

Key points: It was the first time the leaders had met since an infamous meeting in Helsinki a year ago

It was the first time the leaders had met since an infamous meeting in Helsinki a year ago Mr Trump had earlier told reporters that "what I say to him is none of your business"

Mr Trump had earlier told reporters that "what I say to him is none of your business" As well as Mr Putin, the US President met with several other world leaders

The tone of the President's comment, which came after a reporter shouted to Mr Trump about warning Mr Putin "not to meddle" in the 2020 election, was immediately open to interpretation.

Mr Trump answered "of course," before he turned to Mr Putin and said: "Don't meddle in the election."

He playfully repeated the request while pointing at Mr Putin, who laughed.

Mr Trump also did a fist-bump with India's Prime Minister Narendra Modi and Japan's Prime Minister Shinzo Abe. ( Reuters: Kevin Lamarque )

The exchange at the G20 summit in Osaka, Japan, would seem to do little to silence questions about Mr Trump's relationship with Moscow.

It was the first time the leaders had met since they sat together publicly in Helsinki nearly a year ago, when Mr Trump pointedly did not admonish Mr Putin over election interference and did not side with US intelligence services over his Russian counterpart.

Mr Putin disputes special counsel Robert Mueller's conclusion that Russia interfered in the election, telling the Financial Times this week that it was "mythical interference".

"What happened in reality? Mr Trump looked into his opponents' attitude to him and saw changes in American society and he took advantage of this," Mr Putin told the newspaper.

Mr Trump said on Friday that he enjoyed a "very, very good relationship" with Mr Putin, and said "many positive things are going to come out of the relationship".

He said in advance of the meeting with Mr Putin that he expected a "very good conversation" with the Russian leader but told reporters, "what I say to him is none of your business".

Senate Minority Leader Chuck Schumer criticised Mr Trump for kidding around about election meddling. He said the joke is on America and "Putin's the only one laughing".

"President Trump is basically giving Putin a green light to interfere in 2020," Mr Schumer tweeted.

Former President Jimmy Carter had even harsher words. The Democrat said he believed Russian interference put Mr Trump into the White House, though he did not elaborate.

"There is no doubt that the Russians did interfere in the election," Mr Carter said at a human rights discussion in Leesburg, Virginia.

"I think the interference, though not yet quantified, if fully investigated would show that Trump didn't actually win the election in 2016.

"He lost the election and was put into office because the Russians interfered."

May confronts Putin over nerve agent attack

May again confronted Putin over the March 2018 nerve agent attack on double agent Sergei Skripal and his daughter Yulia in the British city of Salisbury. ( AP: Pool/Japan )

The friendly tone of Mr Putin's exchange with Mr Trump stood in sharp contrast to the Russian leader's frosty meeting with outgoing British Prime Minister Theresa May.

Mrs May again confronted Mr Putin over the March 2018 nerve agent attack on double agent Sergei Skripal and his daughter Yulia in the British city of Salisbury.

The two spent weeks in critical condition but eventually recovered.

Britain has accused Russia of poisoning them with the nerve agent Novichok, which Moscow has denied.

Before their meeting — their first since poisonings that also resulted in the death of a British citizen — Mrs May said Britain would push for the two Russian military intelligence officers accused of involvement in the attack to be brought to justice.

She told Mr Putin during the meeting that "there cannot be a normalisation of our bilateral relationship until Russia stops the irresponsible and destabilising activity," according to Downing Street.

Mr Putin has insisted that Russia had nothing to do with the poisoning and argued that bilateral ties were far more important than "the fuss about spies not worth five copecks".

Trump keeps eye on happenings back home

Mr Trump opened the G20 summit in Japan by meeting with the host, Japanese Prime Minister Shinzo Abe, followed by Indian Prime Minister Narendra Modi and Mrs Merkel. ( AP: Susan Walsh/Osaka )

Mr Trump's meeting with Mr Putin came amid a gauntlet of negotiations on international crises, trade wars and a growing global to-do list.

But Mr Trump also kept an eye on the race to replace him back home, where 10 Democrats met in Miami as part of the first debates of the 2020 presidential race.

"I just passed a television set on the way here. I saw that health care and maximum health care was given to 100 per cent of the illegal immigrants coming into our country by the Democrats," Mr Trump said, telling German Chancellor Angela Merkel during their meeting that a debate the previous night "wasn't very exciting".

"So I look forward to spending time with you rather than watching," he said.

Ms Merkel did not react.

Australian Prime Minister Scott Morrison met with Mr Trump ahead of the G20 Summit. ( Twitter: Dan Scavino Jr )

Mr Trump opened the G20 summit in Japan by meeting with the host, Japanese Prime Minister Shinzo Abe, followed by Indian Prime Minister Narendra Modi and Ms Merkel.

He sounded optimistic about inking trade deals with all three and praised alliances he has strained in the past.

Mr Trump and Mr Abe were later joined by Mr Modi and the portion of the meeting open to reporters was convivial: at Mr Trump's urging, the three leaders engaged in a group fist-bump.

AP