Saudi Arabia's Crown Prince Mohammed bin Salman held talks with British Prime Minister Theresa May on the sidelines of the G20 summit in Argentina.
The pair discussed the murder of the journalist Jamal Khashoggi at the Saudi consulate in Istanbul last month.
"The Prime Minister stressed the importance of ensuring that those responsible for the appalling murder of Jamal Khashoggi are held to account, and that Saudi Arabia takes action to build confidence that such a deplorable incident could not happen again," Mrs May's office said in a readout of her meeting with Prince Mohammed.
The prime minister had told reporters on the flight to Buenos Aires that she would speak to the crown prince about Mr Khashoggi's death and the situation in Yemen.
British officials said the meeting would cover a range of topics, including the upcoming peace talks on Yemen to be held in Sweden next week.
Mrs May’s presence at the talks between world leaders is likely to be dominated by the issue of Brexit and the UK’s future global trade as it prepares to leave the European Union in March 2019.
Britain exported more than £6 billion in goods and services to Saudi Arabia in 2017 including machinery, cars and aircraft.
It is also the second-largest major arms supplier to Saudi Arabia, behind the United States, according to the think tank the Stockholm International Peace Research Institute.
The UK imports from Saudi Arabia amounted to some £3 billion with crude oil making up about half of the total.
The crown prince also met briefly with US President Donald Trump on Friday.
A White House official confirmed the two exchanged pleasantries during a leaders’ session.
Mr Trump later said there was “no discussion” but did not rule out holding longer talks with the crown prince during the two-day summit.
Prince Mohammed spoke with other world leaders on the sidelines including Chinese President Xi Jinping.
Saudi Arabia’s press agency posted an image of the pair together but gave no details of what was discussed.
France’s President Emmanuel Macron sought firm talks with the crown prince when they met on Friday, according to a French official.
Prince Mohammed was greeted warmly by Russian President Vladimir Putin.
Kremlin documents showed the pair were due to hold bilateral talks on Saturday.
Earlier on Friday, Prince Mohammed met Indian Prime Minister Narendra Modi and told him about plans to scale up investments in India's tech, farm and energy sectors, an Indian official and the Saudi news agency (SPA) said on Friday.
The two leaders met in the prince's residence in Buenos Aires and discussed Saudi Arabia's readiness to supply India with oil and petroleum products.
Mohammed bin Salman arrives at the G20 - in pictures
Saudi Crown Prince Mohammed bin Salman arrives in Argentina for G20 summit