(Updates market levels, adds currency data)
By Walter Bianchi and Jorge Otaola
BUENOS AIRES, Oct 2 (Reuters) - Argentine stocks and bonds slid on Thursday as the government left markets guessing about policy direction after the appointment of a new central bank chief viewed as sympathetic to the government's ramped-up interventions in the economy.
The benchmark Merval stock index slumped more than 9.2 percent. Traders said financial markets were wary of a possible shift in the regulator's monetary policy to support government efforts to bolster growth in the stagnating economy.
Bond prices also fell as investors digested the nomination of Alejandro Vanoli as the bank's new governor at a time when Argentina is grappling with shrinking foreign reserves, runaway inflation and a tanking currency after defaulting on its debt.
"The stock index's fall is a reaction to the departure of (Juan Carlos) Fabrega who was the only person with common sense in this administration," said Marco Trovato of Buenos Aires-based consultancy Stock Index Forecast.
Traders said the new central bank chief will likely tighten foreign exchange controls in a bid to stanch capital flight.
Vanoli has defended recently the ramping up of state interventions in the economy designed to bolster consumer demand and protect reserves that stand at $27.9 billion, roughly 4-1/2 months' worth of import cover.
His appointment stoked concerns over the central bank's independence and the policy path it will take.
"The fact that the (central bank's) head has been replaced suggests that the central bank's independence will be further diminished," BNP Paribas said in an investor briefing note.
The price of Argentina's over-the-counter bonds fell an average 2.1 percent. The rout was lead by a 4.7 percent fall in the dollar-denominated Bonar 24.
The drop in the Merval was driven by a sell-off in companies also listed in New York. This came two days after Argentine President Cristina Fernandez vowed to crack down on the practice of Argentine investors buying stocks in pesos, only to sell them in New York for dollars through the ADR market.
Cabinet Chief Jorge Capitanich ducked questions about whether the departure of Fabrega, who had pushed for tighter anti-inflation measures but ran up against the powerful economy minister, Axel Kicillof, would mark a shift in monetary policy.
The breach between the black market and official exchange rate has exploded to 85 percent this year as average Argentines line up at the illegal but tolerated exchange houses, called "cuevas" or "caves", that dot urban areas across the country.
The unofficial, or black market peso has weakened more than 36 percent this year to 15.75 per dollar. The official peso exchange rate is down 22.79 percent at 8.445 per greenback this year.
Neither the official nor the black market rate moved much on Thursday.
Fabrega, a career banker oversaw a hike in interest rates and orchestrated a sharp devaluation to protect the regulator's thinning reserves that helped inspire some market confidence earlier in the year. It also left him increasingly alienated from President Fernandez and Kicillof.
"Fabrega's departure will ultimately raise the risk of a currency crisis," said Fiona Mackie, analyst at the Economist Intelligence Unit.
Vanoli's nomination will now be submitted to Congress, though this is a formality and does not stand in the way of the former market regulator taking oath and beginning his duties. (Additional reporting and writing by Richard Lough; Editing by Chizu Nomiyama, W Simon and Diane Craft)