* Benchmark rate unchanged at 3.75%, as expected * C.bank gov: vows to direct all instruments to support economy * Mobility curbs affect some economic activity * Maintains 2021 growth outlook at 4.8%-5.8% (Adds growth, portfolio inflow) JAKARTA, Jan 21 (Reuters) - Indonesia’s central bank held interest rates unchanged on Thursday as it stuck to its 2021 growth forecast, but pledged to continue to support an economy struggling with rising coronavirus cases and tightening restrictions. Bank Indonesia (BI) kept the 7-day reverse repurchase rate at 3.75%, a record low, as expected by the majority of analysts in a Reuters poll. While the head of BI said that rising coronavirus cases in December and January had some impact on economic activity, the central bank continued to expect 4.8%-5.8% growth this year. “We will periodically reassess that based on (progress on) vaccination, global condition, fiscal expansion, capital expenditure and investment growth,” said Governor Perry Warjiyo at a streamed briefing. “Going forward, Bank Indonesia will continue to direct all policy instruments to support the national economic recovery.” Indonesia suffered its first economic recession in over two decades last year as the pandemic hit consumption and business activity, costing jobs. To soften the blow, BI slashed interest rates by 125 basis points in 2020, pumped some $50 billion worth of liquidity into the financial system and relaxed lending rules. The government recently tightened restrictions in some provinces including Jakarta after a resurgence in cases put hospitals under serious strain, even as the country began a mass vaccination campaign earlier this month. Warjiyo said that while household consumption was improving more slowly than expected due to the restrictions, he expected economic growth to continue to rebound in 2021 on growing exports and continued fiscal stimulus. Analysts in the Reuters poll were nearly evenly split on whether monetary easing is in store for 2021 but Gareth Leather, senior Asia economist at Capital Economics said he expected social distancing to remain a drag on the economy for most of the coming year. “We doubt this marks the end of the central bank’s easing cycle,” he said. “The timing of future rate cuts will be determined by the performance of the currency.” Warjiyo said the rupiah was “fundamentally undervalued” and had room to strengthen against the U.S. dollar. He expected portfolio inflows into emerging markets to increase amid greater U.S. fiscal expansion under a Joe Biden presidency and continued loose monetary policy. BI forecast a $19.1 billion portfolio inflow into Indonesian financial markets this year, up from $11 billion last year, Warjiyo said. Bank Danamon economist Wisnu Wardana meanwhile said he saw a “good chance” of a rate cut next month if the official full-year 2020 GDP figure, due to be released next month, came in below BI expectations. BI is forecasting a 1% to 2% contraction in 2020. (Additional reporting by Tabita Diela; Editing by Ana Nicolaci da Costa)