MEXICO CITY, Dec 15 (Reuters) - Mexico’s state-oil giant Petroleos Mexicanos (Pemex) said on Tuesday it carried out a debt operation that would allow it to cover short-term financial liabilities worth 96 billion pesos ($4.85 billion). The operation will give the ailing oil company some relief over the coming months, but it still needs to find billions of dollars more over the coming years to repay bond holders. “This financial operation is part of a set of steps Pemex took since the beginning of the COVID-19 crisis to mitigate the drop in income while not increasing public debt beyond the ceiling approved by the federal congress,” it said in a statement.