King Salman of Saudi Arabia will arrive in Russia this week to conduct the first official visit to the country by a Saudi king, a senior Kremlin aide said on Monday.

“We are awaiting the king's visit on Thursday,” President Vladimir Putin's foreign policy aide, Yury Ushakov, was quoted by the state TASS news agency as saying.

Saudi Arabia's ministry of information called the visit by 81-year-old Salman “historic” as it would be the first official visit to Russia by a Saudi monarch. Putin had visited Riyadh in 2007.

The visit comes a month before members of the OPEC oil cartel, of which Saudi Arabia is the biggest producer, are due to meet with the other nations that have joined them in cutting crude output, including Russia, to discuss extending the pact that has helped prop up prices.

King Salman is expected to ask Russia's support and commitment to ensure that the production cuts deal continues, following Saudi Arabia's cut of its output to around 10 million barrels per day to help control a glut in world oil supplies.

OPEC and its allies agreed from the beginning of 2017 to cut their production by around 1.8m barrels per day for six months. It was subsequently extended through March 2018. The pact has helped reduce crude supplies on the market and the price to climb to around $55 per barrel currently.

“King Salman does not do courtesy calls so it can be reasonably assumed that his first official visit to the Russian capital is a serious event,” wrote Chris Weafer, a senior partner at Macro-Advisory, a consultancy.

“It is not too many years ago that such a visit would have been difficult, if not impossible. Today that has changed 180 degrees. Both countries now see political and economic advantages from a closer, albeit pragmatic, relationship.”

Saudi Arabia and Russia are heavily dependent on oil exports and the plunge of the price of crude that began in 2014 lashed both of their economies. While Russia and Saudi Arabia are now allies on the global oil market, they are on the opposite sides in the Syria conflict, with Moscow supporting the regime of President Bashar al-Assad and Riyadh backing the opposition.

Another potential point of disagreement between Riyadh and Moscow could be Yemen, where a Saudi-led coalition has been bombing Huthi rebels since 2015, drawing criticism from Moscow.