* Brazil's real loses for fifth straight day, stocks also down * Mexican peso hit by electricity sector ructions * Latam vaccinations need to pick up- PAHO (Adds details, updates prices) By Susan Mathew and Ambar Warrick March 3 (Reuters) - Brazil's real tumbled to a four-month low on Wednesday on downbeat data and economic uncertainty, while Mexico's peso led losses across Latin American currencies on the prospect of new tensions between the government and the private sector. The real was down 1.6% at 5.7591 to the dollar, losing ground for a fifth straight session as it hit levels last seen in November. Private sector business activity in Brazil shrank in February for the second month in a row, a survey showed, while separate data showed that the economy contracted 4.1% in 2020 - the worst drop in decades, but not as much as originally expected. The government also noted high uncertainty over economic growth in 2021 due to the pandemic. "There is strong evidence to suggest that the recovery has slowed so far this year, and the worsening COVID-19 outbreak is casting a dark cloud over the outlook for the next few months at least," said William Jackson, chief EM economist at Capital Economics. Concerns over government interference hit Brazil's Bovespa share index, which plunged 3% on losses in financial and energy stocks. State oil firm Petrobras slipped after it said four board members would step down, following the removal of its chief executive by President Jair Bolsonaro last week. Mexico's peso led losses across Latam currencies, plunging 1.9% as the Mexican Senate also approved controversial legislation that will give priority in electricity dispatch to the state power utility, giving it an edge over private players. The legislation, coupled with President Andres Manuel Lopez Obrador saying the country plans to renegotiate electricity contracts, heralded fresh tensions with private power producers. Analysts saw the move as a risk for private investment in the country's energy sector. Meanwhile, the state oil company Petroleos Mexicanos (Pemex) said on Tuesday that it had ended a contract with the credit ratings agency Fitch, which has downgraded Pemex bonds to speculative or 'junk' grade. Concerns over government meddling in major Latam economies, coupled with the steady spread of the virus in the region, have hurt Latam risk assets this year, with most of them lagging their broader emerging market peers. The Pan American Health Organization (PAHO) also said faster COVID-19 vaccinations are needed in Latam to curb rise of dangerous variants, such as the one seen in Brazil. Key Latin American stock indexes and currencies: Latest Daily % change MSCI Emerging Markets 1374.15 1.07 MSCI LatAm 2174.13 -2.65 Brazil Bovespa 108253.74 -2.95 Mexico IPC 46424.17 1.62 Chile IPSA 4787.35 1.42 Argentina MerVal 47362.97 -1.588 Colombia COLCAP 1351.57 0.11 Currencies Latest Daily % change Brazil real 5.7591 -1.62 Mexico peso 20.9877 -1.87 Chile peso 726.9 0.21 Colombia peso 3679.35 -0.68 Peru sol 3.6727 -0.19 Argentina peso 90.2200 -0.07 (interbank) (Reporting by Susan Mathew in Bengaluru; Editing by Kevin Liffey and Nick Zieminski)