Saudi Arabia's Crown Prince Mohammed bin Salman held talks with Russian President Vladimir Putin on Monday, where they discussed the relationship between the two countries.
They also discussed developments in Syria and Yemen, and “the importance of combating extremism and terrorism and working to dry up its sources”, the Saudi state press agency Spa reported.
The Russian president also met King Salman.
Before his visit this week, Mr Putin said he could play a role in easing tension in the Arabian Gulf after a spate of attacks on international shipping and major oil facilities in the kingdom.
Speaking to Arabic news media, Mr Putin, whose last visit to the kingdom was in 2007, highlighted his good ties with Gulf states and Iran.
However, he said he had no reliable information on who carried out the September 14 attacks on Saudi oil facilities in Abqaiq and Khurais.
Yemen's Houthi rebels said they carried out the drone and missile strikes, but Riyadh and Washington blamed Tehran, which denied responsibility.
"Imagine, we don't know. The next day, I asked the head of the foreign intelligence service and the defence minister. 'No, we don't know'," he said, an Arabic-language transcript provided by Saudi-owned Al Arabiya television showed.
“It is wrong to determine who is guilty before it is known reliably and clearly who is behind this act,” Mr Putin said.
The Russian president said he had agreed to help investigate.
also said he had "very friendly personal relations" with Prince Mohammed.
Russia has built a working relationship with Iran in Syria, where both sides back the regime of Bashar Al Assad in the eight-year civil war.
The two sides co-ordinate military efforts in the war but Mr Putin has led a separate set of negotiations in Astana bringing sides in the conflict together. He has also led talks with Turkish President Recep Tayyip Erdogan and Iranian President Hassan Rouhani regarding the situation in north-west Syria.
Asked about the September 14 attack while at a meeting with the Iranian and Turkish presidents, Mr Putin quipped that perhaps Riyadh would be interested in following Ankara by buying Russian S-400 air defence systems.
Tension in the Gulf has risen to new highs since May last year, when the United States withdrew from a 2015 international nuclear accord with Tehran that put limits on its nuclear enrichment in exchange for the easing of sanctions.
US President Donald Trump reinstated sanctions, increasing pressure on Iran's economy.
Throughout the summer there was a significant increase in attacks from Houthi rebels, who fired dozens of missiles and drones at civilian and military infrastructure in Saudi Arabia. There were also a number of attacks on Gulf shipping, with several tankers – including an Iranian vessel last week – being hit.
Saudi Minister of State for Foreign Affairs Adel Al Jubeir said Riyadh was not behind a suspected strike against the Iranian-owned oil tanker in the Red Sea on Friday. Washington and close allies blamed Iran for the other attacks on shipping, which Tehran denies.
Iran's Islamic Revolutionary Guard Corps also detained a British oil tanker and its crew while it travelled in international shipping channels.
The UK government said the move was illegal.
Mr Putin said such attacks strengthened co-operation between oil producers inside and outside Opec and that Russia would work with its partners to reduce attempts to destabilise markets.
Russia and Saudi Arabia, two of the world's biggest oil producers, have worked together to establish oil production agreements through an alliance known informally as Opec+.
While Mr Putin said he could help to ease tensions, he also said the region's leaders did not need advice or mediation.
“You can only talk to them out of friendship,” he said.
“I know that they, being smart, will listen and analyse what they are told. In this context, we can play a positive role.”
Asked if he backed calls from Mr Trump for new talks on Iran's nuclear limits and its ballistic missile programme concurrently, Mr Putin said that the two issues should be dealt with separately.
"Most likely it [the missiles] can and should be discussed … the missile programme is one thing and the nuclear programme is another," he said.
"Of course, this is necessary, but there is no need to merge one with the other"
On Syria, Mr Putin said any new constitution that is drawn up should guarantee the rights of all ethnic and religious groups. A congress convened by Russia last year gave the United Nations envoy for Syria the task of forming a committee to draft a new constitution, after many rounds of talks to end the war failed.
UN officials say the recent formation of the constitutional committee was crucial in leading to political reforms and new elections meant to unify Syria and end the civil war.
The new committee is scheduled to meet for the first time on October 30.
Mr Putin also said Syrians “interact positively” with Russian military police and soldiers stationed in the country.
On rocky relations with America, Mr Putin said Moscow did not blame Mr Trump for not improving ties. Instead, the Russian leader blamed the lack of progress on the "internal political agenda".