Saudi Crown Prince Mohammed bin Salman met Russian President Vladimir Putin on the sidelines of G20 summit in Argentina on Saturday and discussed areas of cooperation including rebalancing the world oil market, the Saudi Press Agency reported.

The Organization of the Petroleum Exporting Countries, of which Saudi Arabia is a key member, and Russia and other leading oil producers will meet in Vienna on Dec 6-7 to discuss the oil market, as prices have been declining due to oversupply.

Riyadh has suggested OPEC and its allies reduce output by 1 million barrels per day from January 2019 to stem the price falls.

Speaking in Buenos Aires, Putin said on Saturday that he had no concrete figures on possible output cuts but that Russia would continue contributing to reducing global output.

On Friday, Putin and the crown prince, heir to the throne of the world's top oil exporter, exchanged a high-five as they took seats next to each other at a plenary session of the Group of 20 summit.

Putin's friendly behaviour contrasted sharply with that of other leaders at the summit, amid suspicions of the prince's possible involvement in the killing of Saudi journalist Jamal Khashoggi at the Saudi consulate in Istanbul in October.

Saudi Arabia has said the prince had no prior knowledge of the murder, which has strained Saudi ties with the West and battered the prince's image abroad.

Russia has refrained from criticising Saudi Arabia or the crown prince over the killing. Putin said in October he lacked information about the matter and said Russia would not tear up its relations with Saudi Arabia because of it.

However, Moscow has also fostered strong ties with Saudi Arabia's regional arch foe Iran. Russia and Iran back President Bashar al-Assad in Syria's civil war, while Saudi Arabia along with Western countries have backed some rebel groups.

Putin is expected to visit Riyadh, but the timing of visit has not yet been finalised.

(Reporting by Nayera Abdallah in Cairo and Marwa Rashad in Riyadh; Editing by Peter Graff and Hugh Lawson)