By Dave Graham and Miguel Gutierrez MEXICO CITY (Reuters) - Divisions within Mexico's main conservative opposition party have erupted into a bitter public dispute that threatens to undermine the reform agenda of President Enrique Pena Nieto. Short of a majority in Congress, Pena Nieto's Institutional Revolutionary Party (PRI) is likely to need support from the conservative National Action Party, or PAN, to see through plans to overhaul state oil giant Pemex and broaden the tax base.

By Alexandra Alper and Dave Graham MEXICO CITY (Reuters) - Mexico's main opposition parties said on Tuesday they would resume talks on sweeping reforms with the government, lifting a cloud over a cross-party pact that is the axis of President Enrique Pena Nieto's economic agenda. Opposition leaders said they had agreed on new measures with President Enrique Pena Nieto's ruling Institutional Revolutionary Party (PRI) to preserve the pact, which is aimed at fueling growth in Latin America's no. 2 economy.

Fitch Ratings upgraded Mexico's sovereign credit rating on Wednesday, citing what it called the country's strong economic fundamentals and commitment to structural reforms. The international ratings agency increased Mexico's credit score by one notch to BBB+ from BBB and stated that its rating outlook was stable. "The upgrade of Mexico's sovereign ratings reflects its strong macroeconomic fundamentals, including the absence of macro-financial imbalances, consistent adherence to its inflation targeting and flexible exchange rate regimes," Fitch said in a statement.

By Mark Felsenthal and Steve Holland MEXICO CITY (Reuters) - U.S. President Barack Obama gave his blessing on Thursday to a new security arrangement with Mexican leader Enrique Pena Nieto, in which Mexico will make reducing violence a priority over hunting drug cartel kingpins in the war against organized crime. The two presidents said they also want to step up trade and business ties that have been overshadowed by the battle against drug trafficking.