FRANKFURT (Reuters) – Uniper, Germany’s largest importer of Russian gas, on Tuesday said its net debt rose more than six-fold in the first quarter, blaming higher liquidity needs to cover huge swings in energy prices. Economic net debt stood at 1.98 billion euros ($2.08 billion) at the end-March, compared with 324 million euros at the end of December, the utility said. ($1 = 0.9518 euros) (Reporting by Christoph Steitz; Editing by Riham Alkousaa)