EMERGING MARKETS-Latam currencies slide as China worries dent risk appetite

* S&P revises Hungary outlook to "negative" from "stable" * China unexpectedly cuts key rates as economic data disappoints * Brazil's Petrobras to cut gasoline prices by 4.9% from Tuesday (Updates prices; adds bullets, comments, details) By Susan Mathew and Anisha Sircar Aug 15 (Reuters) - Brazil's real and Mexico's peso fell against the dollar on Monday, tracking other emerging market currencies as worries about China's economic growth dented risk appetite, while Hungary's forint was set for its worst session since May against the euro. The forint's 1.7% slide was triggered by S&P lowering Hungary's credit rating outlook to negative from stable. S&P said external risks, including potential cuts to European Union funds and reduced gas flows, could weigh on Hungary's growth prospects, already pressured by surging inflation and a fiscal adjustment to rein in the budget deficit. The forint has slumped more than 7% so far this year, far underperforming other central and eastern European currencies. A broader basket of emerging market currencies is down about 4%. Global sentiment took a hit on Monday after weak retail sales and factory activity in China raised worries about slowing growth in the world's second largest economy, prompting its central bank to cut a key lending rate to stimulate demand. This sent the safe-haven dollar rallying. "The first impression from the latest set of activity data for July is that there are few signs of a strong rebound in the (Chinese) economy," said Charlie Lay, FX and EM analyst at Commerzbank. "Consumer sentiment is likely to remain fragile given uncertainties over future outbreaks and lockdowns. Furthermore, the economy is still battling with the property correction and weak investment in general." China is a major destination for commodity exports from resource-rich Latin America. Brazil's real lost 0.5%, after three weeks of gains. Investors seemed to look past data showing economic activity rose more than expected in June, helped by a service sector rebound following the impact of the COVID-19 pandemic. The country's central bank chief defended policymakers' focus on 12-month inflation through March 2024, contributing to signals that the bank may be done raising interest rates. Brazil stocks edged 0.2% higher. Oil company Petrobras rose 0.4% after saying it would lower refinery gate gasoline prices by 4.9% from Tuesday, while Vale dropped 2%. The miner was fined about 86.3 million reais ($16.82 million) after the country's comptroller general decided the company did not present truthful information on the conditions of its Brumadinho tailings dam prior to a 2019 disaster. Mexico's peso lost 0.1%, breaking a five-session winning streak. Most other Latin American markets were closed for local holidays. Key Latin American stock indexes and currencies at 1900 GMT: Stock indexes Latest Daily % change MSCI Emerging Markets 1013.57 -0.32 MSCI LatAm 2258.89 -0.01 Brazil Bovespa 113086.81 0.29 Mexico IPC 48864.49 0.02 Chile IPSA 5394.91 1.3 Argentina MerVal 125979.57 2.145 Colombia COLCAP 1330.82 0.48 Currencies Latest Daily % change Brazil real 5.0979 -0.49 Mexico peso 19.8743 -0.23 Chile peso 873.9 0.00 Colombia peso 4157.13 -0.02 Peru sol 3.8491 0.00 Argentina peso 134.5800 -0.23 (interbank) Argentina peso 290 2.41 (parallel) (Reporting by Susan Mathew in Bengaluru; Editing by Kirsten Donovan)