MOSCOW, Dec 23 (Reuters) - Russia"s commodity-dependent economy will slow in 2022 as the central bank will have to keep rates high for several months before stubbornly high inflation starts waning, a Reuters poll showed on Thursday. After shrinking 3% in 2020, its sharpest contraction in 11 years, the Russian economy has recovered to pre-pandemic levels thanks to a rebound in consumer demand and high prices for oil, its key export. But it is expected to lose momentum. The average forecast of 19 analysts polled in December suggested economic growth will slow to 2.5% in 2022. President Vladimir Putin said on Thursday the economy was expected to grow 4.5% in 2021. "The economy will start slowing after fiscal and monetary stimuli are withdrawn," said Sergey Konygin, chief economist at Sinara Investment Bank. The central bank, which raised the key interest rate seven times in 2021 from a record low of 4.25%, is expected to hike it to 9% in the first quarter of 2022 (RUCBIR=ECI). The Bank of Russia is expected to lower the rate gradually to 8% by year-end, with forecasts ranging from 7% to 8.5%, the poll showed. Higher rates are needed to tame stubbornly high inflation that reached 8.4% in November, a level last seen in early 2016, and was hovering at 8.2% in late December. "Inflation passed its peak in November and will gradually slow," said Kirill Sokolov, chief economist at Sovcombank. Higher rates can also support the rouble by making investments into high-yielding rouble assets more attractive. A decline in geopolitical tensions and the return of foreign investors to Russian assets should also support the rouble, said Konygin. The average of forecasts in the poll suggested the rouble will trade at 71.70 to the dollar and 83.40 to the euro 12 months from now, compared with forecasts of 72.50 and 84.09 respectively in the previous poll. "For the rouble to firm substantially past 70 versus the dollar, inflationary expectations need to decline substantially, for which inflation must slow down first," said Alexander Isakov, chief economist at VTB Capital. Most of the forecasts in the Reuters poll were based on at least 10 individual projections. Reporting by Andrey Ostroukh with additional polling by Elena Fabrichnaya Editing by Mark Heinrich