May 8 (Reuters) - Citigroup (C.N), opens new tab must face a revived lawsuit claiming it caused more than $1 billion of losses by orchestrating and concealing a vast fraud at the now-bankrupt Mexican oil and gas services company Oceanografia, a U.S. appeals court ruled on Thursday.

A three-judge panel of the 11th U.S. Circuit Court of Appeals in Miami said 30 Oceanografia vendors, creditors and bondholders adequately alleged that Citigroup substantially aided the fraud, and a lower court judge erred in dismissing the nine-year-old case.