King Salman of Saudi Arabia will visit Russia on Thursday, senior Kremlin aide Yury Ushakov was quoted by the TASS news agency as saying.
"We are awaiting the king's visit on Thursday," Ushakov said Monday, without elaborating.
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.
OPEC and its allies agreed from the beginning of 2017 to cut their production by around 1.8 million barrels per day for six months. It was subsequently extended through March 2018.
The pact has helped reduce the glut of crude supplies on the market and the price to climb to around $55 per barrel currently.
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.
Moscow supports the regime of President Bashar al-Assad while Riyadh supports the opposition.
At least 3,000 people including 955 civilians were killed in September, the deadliest month of the conflict this year, the Syrian Observatory for Human Rights monitor said on Sunday.