Data on Monday showed that the vaccine, jointly developed by AstraZeneca and the University of Oxford, produced an immune response in early-stage clinical trials.

AstraZeneca has signed agreements with governments around the world to supply the vaccine should it prove effective and gain regulatory approval. It has already signed deals to produce and supply over 2 billion doses of the shot, with 300 million doses earmarked for the United States.

SK Bioscience, a unit of SK Chemicals, said it will start producing undiluted solutions of the vaccine after discussing production plans with AstraZeneca.

The manufacturing contract, which begins this month, will last until early next year and could be extended depending on AstraZeneca's success in development of the vaccine, SK said.

South Korea's health ministry arranged discussions between the two companies and will also begin discussions with AstraZeneca to introduce the vaccine to the country, it said.

The World Health Organization's chief scientist has said the vaccine, called AZD1222, is the leading candidate in a global race to halt a pandemic that has killed more than 600,000.

AZD1222 was developed by Oxford University and licensed to AstraZeneca, which has put it into large-scale, late-stage trials to test its efficacy.

(Reporting by Sangmi Cha; Editing by Jason Neely and Tom Hogue)