LONDON (Reuters) - European regulators confirmed on Friday that Roche's blockbuster cancer drug MabThera, also known as Rituxan, was safe to use, following a contamination scare at a factory in the United States.

The bacteria Leptospira licerasiae was detected at an early stage of the manufacturing process in bioreactors at Roche's facility in Vacaville, in the latest example of manufacturing problems that can hit major drugmakers.

However, the contaminant was not found at later stages of production and the European Medicines Agency said all material in which the bacteria had been detected was discarded.

"The European Medicines Agency's Committee for Medicinal Products for Human Use (CHMP) has concluded that the batches of the active substance of MabThera, rituximab, produced at the Vacaville manufacturing site in the United States do not present a risk to public health," the watchdog said.

L. licerasiae can cause leptospirosis, a water-borne disease transmitted from animals to humans.

MabThera is used to treat non-Hodgkin's lymphoma and chronic lymphocytic leukaemia, as well as rheumatoid arthritis.

(Reporting by Ben Hirschler)