BUENOS AIRES, April 14 (Reuters) - Argentine stocks inched higher in choppy trade on Monday, pushed up by Brazil's Petrobras after news the company may have made the biggest oil discovery in 30 years, traders said.
The benchmark MerVal stock index .MERV rose 0.26 percent to 2,120.71 points.
The offshore find, known as Carioca and made in partnership with Repsol-YPF REP.BA and BG Group BG.L, could contain 33 billion barrels of oil equivalent, said Harold Lima, head of Brazil's National Petroleum Agency.
Buenos Aires-listed shares of state-owned Petrobras (APBR.BA) soared 7.9 percent to 194.2 pesos, moving a volume of $16.2 million, the equivalent of 34.7 percent of total value on the MerVal.
Repsol skyrocketed 17.2 percent to 140 pesos, but the impact remained limited due to low volume.
"Bank weaknesses reappeared but Petrobras changed the index's fortune," said Marcelo Paccione, an analyst at ConsulCapital brokerage.
Among the session's losers were banking groups, Banco Hipotecario BHI.BA, which shed 2.4 percent to 1.7 pesos, and Grupo Financiero Galicia (GFG.BA), which fell 1.4 percent to 2.2 pesos.
In the broader market, volume swelled to a healthy $46.6 million. Of the active issues, 40 declined, 27 advanced and 18 ended unchanged.
On the debt market, government bonds <AR/BONOS> rose 0.2 percent on average. The session's gainers were led by the dollar-denominated Discount bond, which was up 0.4 percent.
Meanwhile, the peso closed unchanged at 3.1525/3.1550 ARS=RASL per dollar in formal interbank trade, where the central bank regularly intervenes.
In informal trade between foreign exchange houses, as measured by Reuters, the peso ARSB= appreciated 0.24 percent to 3.1800/3.1825. (Reporting by Walter Bianchi and Jorge Otaola; Writing by Gaspard Sebag; editing by Gary Crosse)