The European Medicines Agency (EMA) did not name the company it expects to file the application, but Pfizer Inc and BioNTEch are the most advanced in the regulatory process among the three companies that have published late-stage trial data for their vaccines.

The companies applied on Nov. 20 for U.S. approval and the UK said it has asked its medical regulator to assess the vaccine for its suitability.

Asked about its co-operation with the U.S. Food and Drug Administration (FDA), it said in an email the agency may not be able to synchronise the decision making process with other international regulators.

The EMA started a real-time review of the Pfizer-BioNTech vaccine on Oct. 6 to speed up the process of approving a successful vaccine in the bloc, by allowing researchers to submit findings in real time, without waiting for studies to conclude.

(Reporting by Francesco Guarascio in Brussels; Writing by Josephine Mason in London; Editing by David Goodman and David Evans)