(Updates with final prices) SAO PAULO, April 10 (Reuters) - Brazil's currency and stocks seesawed on Monday, reflecting uncertainty over the passage of a proposed pension reform and the impact of sliding iron ore prices in China.

Brazil's real weakened as much as 0.2 percent before closing up 0.18 percent at 3.137 per dollar. The benchmark Bovespa stock index likewise fell in early trading before closing very slightly up.

Investors are gauging the difficulty of passing a reform to cut social security expenses by 700 billion reais ($223 billion) over the next decade. In recent days, informal polls by local media have indicated a lack of congressional support for the plan, which senior government officials are trying to downplay.

Expectations that the central bank will cut its benchmark Selic overnight lending rate by a full percentage point on Wednesday have been offset by a wait-and-see approach to the reform agenda, the cornerstone of President Michel Temer's plan to pull Brazil from its worst economic recession on record.

"There was no progress in the pension reform process since the last interest-rate meeting" almost 45 days ago, said a research report by Itaú BBA, noting that "resistance in Congress seems to be growing." Preferred shares of Itaú Unibanco Holding SA, the stock with the largest weighting in the Bovespa, fell 0.18 percent. The bank won a 25 billion-real ($8 billion) tax case with the government on Monday, although it can be appealed by tax agency officials.

Preferred shares of Vale SA, the world's top iron ore producer, shed as much as 2 percent during the session as prices for the mineral fell in China, but closed almost flat.

Key Latin American stock indexes and currencies at 2200 GMT: Stock indexes daily % YTD % Latest change change MSCI Emerging Markets 958.64 0.07 11.1 MSCI LatAm 2643.76 -0.17 12.95 Brazil Bovespa 64649.81 0.09 7.34 Mexico IPC 49540.26 0.4 8.54 Chile IPSA 4900.42 0.25 18.04 Chile IGPA 24543.96 0.29 18.37 Argentina MerVal 20926.18 0.95 23.69 Colombia IGBC 10234.51 0.58 1.05 Venezuela IBC 45387.6 -1.36 43.15 Currencies daily % YTD % change change Latest Brazil real 3.137 0.18 3.74 Mexico peso 18.6870 -0.06 11.01 Chile peso 652.8 0.41 2.74 Colombia peso 2860 0.00 4.76 Peru sol 3.245 0.00 5.21 Argentina peso (interbank) 15.200 0.85 4.44 Argentina peso (parallel) 15.58 0.38 7.96 ($1 = 3.14 reais) (Reporting by Guillermo Parra-Bernal and Claudia Violante; Editing by Dan Grebler and Biju Dwarakanath)