BUENOS AIRES -- Crown Prince Mohammed bin Salman of Saudi Arabiainfo-icon exchanged laughs and clasped hands with Russian President Vladimir Putin on Friday in an incongruously celebratory moment as they took their seats among other worldinfo-icon leaders for a meeting in Buenos Aires during an economic summit.

It was the surest sign yet that the crown prince can still expect a warm welcome from at least some heads of state even after American intelligence agenciesinfo-icon and many Western officials have concluded that he authorized the killing of Jamal Khashoggi, a Virginia resident and Washington Post columnist ambushed two months ago by Saudi agents in a consulate in Istanbulinfo-icon. The prince has denied advanced knowledge of the killing.

The Group of 20 summit meeting, a gathering of the leaders of the world's largest economies, is a closely watched test for Crown Prince Mohammed, the 33-year-old favorite son of the aging King Salman and de facto ruler of the oilinfo-icon-rich kingdom.

An Argentine prosecutor has begun an inquiry into potential criminal charges against the crown prince for human rightsinfo-icon abuses, including allegations that he was responsible for the torture of Mr. Khashoggi and certain Saudi prisoners, as well as for warinfo-icon crimes committed by Saudi-led forces fighting in Yemeninfo-icon. Legal authorities said there was no chance of any action against Prince Mohammed during the two-day meeting, but some world leaders had said that they might seek to confront him over the killing.

French President Emmanuel Macron appeared to do just that, as he had promised. When he met with Prince Mohammed on the sidelines of the summit, a microphone captured fragments of their dialogue. Mr. Macron stood in a gray suit with a stern face just inches from Prince Mohammed, nodding his head and smiling awkwardly.

"Don't worry," the crown prince told the French president.

"I do worry. I am worried," Mr. Marcon responded. "I told you."

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"You told me. Thank you very much," Prince Mohammed said, bowing his head almost bashfully.

"You know what I mean," the French president continued, adding moments later, "You never listen to me," and "I am a man of my word."

"I do listen to you," Prince Mohammed insisted, adding, "It's O.K., I can deal with it."

The crown prince also met Friday with Prime Minister Narendra Modi of Indiainfo-icon, whose country sends many temporary migrant workers to Saudi Arabia. But a video clip of Prince Mohammed's encounter with Mr. Putin was the most talked about image of the day, in part because of the delight the two leaders appeared to take in their meeting.

Mr. Putin also faced international criticism over a murder this year. Britaininfo-icon has concluded that Mr. Putin's government ordered the killing of a former Russian spy living near London, a charge the Kremlin denies.

Approaching seats next to each other at a round-table at the summit meeting, they clapped their palms together in the air as though in a high-five. As their handshake continued, the prince patted Mr. Putin three times on the back of his hand, and they continued to laugh together as though enjoying a joke.

The advocacy group Human Rights Watch had petitioned the Argentine courts this week for a criminal investigation into Prince Mohammed's potential responsibility for rights abuses, under a broad jurisdiction for such crimes in Argeninian law. Although it cited the Khashoggi killing, the petition focused primarily on the Saudi-led military intervention in Yemen. The United Nationsinfo-icon has called the war in Yemen the world's worst man-made humanitarian disaster, and United Nations experts have said both sides may have committed war crimes.

Judge Ariel Lijo formally requested information on Wednesday from Argentinainfo-icon's foreign ministry about guarantees of legal immunity given to Prince Mohammed while he was attending. The judge also requested information from Turkeyinfo-icon, Yemen, the International Criminal Courtinfo-icon and elsewhere to begin evaluating the allegations.

President Mauricio Macri of Argentina said Thursday that the crown prince's potential role in the killing of Mr. Khashoggi was a legitimate subject for discussion at the meeting of the Group of 20, an association of the leaders of the world's biggest economies.

"This issue that has impacted the world is on the table and maybe it will come out in bilateral meetings or in the agenda of the G-20," Mr. Macri said at a news conference in the Argentine capital.

Mr. Macron of Franceinfo-icon had said he intended to bring up the killing with Prince Mohammed. "I've always been very clear about the issue of Saudi Arabia and I will inevitably have the opportunity to discuss it with the Saudi crown prince," Mr. Macron said at the same news conference.

"Personally, I'm in favor of transparency and associating the international community in this affair, because the whole world is concerned," he said.

A French official said Friday that Mr. Macron had sought to discuss the Khashoggi killing, the Yemen war and the oil markets with the prince during their one-on-one conversation.

President Trumpinfo-icon, for his part, said before leaving Washington on Thursday that he would have been happy to meet one-on-one with Prince Mohammed but the summit schedule was already booked. "I would have met with him but we didn't set that one up," Mr. Trump said.

Mr. Trump has emphasized Saudi Arabia's importance to the United Statesinfo-icon as a weaponsinfo-icon buyer, source of oil and ally against Iraninfo-icon, and he has sought to cast doubt on the conclusion of intelligence agencies that Prince Mohammed knew in advance about the Khashoggi killing. "Maybe he did and maybe he didn't," the president said last week in a dictated statement.

Prince Mohammed, who has denied ordering or having advance knowledge of the killing, kept a low profile Thursday. He arrived in Buenos Aires on Wednesday, after a weeklong tour of Arab capitals, and he was welcomed at the airport by the host country's foreign minister, Jorge Faurie.

Officials of Human Rights Watch said Thursday that its petition to the Argentine courts had already shaped the atmosphere at the summit meeting for Prince Mohammed.

"No world leader attending the G-20 summit today can ignore the fact that Mohammed bin Salman is under scrutiny for alleged war crimes in Yemen and torture," said Jose Miguel Vivanco, the Americas director at Human Rights Watch.

The story was first published in The New York Times