(Recasts with office's confirmation, adds Moderna reaction in paragraph 2, share reaction in paragraph 3, adds background in para 5)

FRANKFURT, Nov 21 (Reuters) - The European Patent Office declared a contested mRNA patent owned by Moderna invalid on Tuesday, the office said, handing a win to BioNTech and its partner Pfizer in a patent dispute between the two coronavirus vaccine makers.

Moderna said in a statement that it disagreed with the office's decision and would lodge an appeal.

Shares in Moderna were down 2.3% in premarket trading on Wall Street after the decision was announced by BioNTech earlier on Tuesday.

BioNTech welcomed the decision, calling the patent office's decision "an important one, as we believe that this and others of Moderna's patents do not meet the requirements for grant and should never have been granted."

Moderna has sued BioNTech in Germany and other countries, alleging that it had copied mRNA technology that Moderna had patented well before COVID-19 emerged in 2019.

(Reporting by Ludwig Burger and Patricia Weiss; editing by Matthias Williams, Kirsten Donovan)