Russian oil output stood at 10.83 million barrels per day (bpd) in May, slightly down for a second straight month but still close to a record high reached earlier this year.
Russia, the world's top oil producer, had been steadily increasing oil output despite a fall in global oil prices as a weaker rouble helped to offset oil companies' losses.
OPEC meets on Thursday in Vienna after major crude producers in April failed to seal a deal to freeze output to help the market stabilize.
Arkady Dvorkovich, Russian deputy prime minister, was quoted by TASS news agency as saying on Thursday that Russia was still ready to discuss an oil production freeze if all OPEC nations supported the idea. Russia is not a member of the cartel.
"Of course, if everyone has a united position then Russia of course will look into this question," Dvorkovich said.
Preliminary data from the Russian energy ministry showed on Thursday that Russia produced 45.79 million tonnes of oil last month - or 10.83 million bpd as an average, down from 10.84 million bpd in April.
Russian oil output hit its highest in nearly 30 years in March at 10.91 million bpd. According to the latest data, Lukoil and production sharing agreement projects were among those with lower output last month.
Monthly production at Gazprom Neft, the oil arm of state gas company Gazprom, rose.
For some companies, energy ministry data differs from their consolidated results as the ministry does not attribute some production units to them.
Gazprom Neft, which recently launched commercial production at its Arctic Novoportovskoye field, also plans to launch the Messoyakha oil field, a joint venture with Rosneft, in the fourth quarter of 2016.
Oil prices were steady on Thursday on mixed market signals ahead of the OPEC meeting. Analysts said the meeting was not expected to result in restrictions on crude output.
As oil prices rebound from multi-year lows of around $27 per barrel in January to just under $50 now, Russian Energy Minister Alexander Novak said talks over a potential freeze may now be off the table as "market rebalancing factors start to work step by step."
According to energy ministry data, gas production in Russia was at 46.11 billion cubic meters (bcm) last month - or 1.49 bcm per day, compared to 49.88 bcm in April, or 1.66 bcm per day.