June 19 (Reuters) - The U.S. Food and Drug Administration declined to approve Nabriva Therapeutics Plc's antibiotic for complicated urinary tract infections, citing still-unresolved manufacturing issues, the biopharmaceutical company said on Friday.

Nabriva said in a statement that the complete response letter from the FDA for the resubmission of the new drug application for Contepo, for injection, cited observations at the company's manufacturing partners that could not be resolved due to the FDA's inability to conduct onsite inspections because of travel restrictions from the coronavirus outbreak.

The FDA did not request any new clinical data and did not raise any other concerns with regard to the safety or efficacy of Contepo, Nabriva said.

In April last year, the FDA had declined to approve Nabriva's antibiotic, asking the company to address issues relating to manufacturing deficiencies at one of its contract manufacturers.

"In general, previously identified product quality and facility inspection related observations at our contract manufacturing partners are required to be satisfactorily resolved before the NDA (new drug application) may be approved," Nabriva said in the statement.

Contepo, chemically known as fosfomycin, is the first intravenously administered drug from a class of antibiotics called epoxide in the United States.

Fosfomycin was first discovered in 1969 and has been used to treat a variety of serious bacterial infections including complicated urinary tract infections in countries outside the United States.

The company said it plans to request a meeting with the FDA to discuss the next steps and the FDA's plans for completing foreign facility inspections.

(Reporting by Kanishka Singh in Bengaluru; Editing by Leslie Adler)