Brazil's national health regulator said Thursday its decision to reject the Russian-made Sputnik V vaccine was based on the developer's own data, after the latter threatened to sue for defamation. The Brazilian agency, Anvisa, based the decision on evidence the vaccine carried a live version of a common cold-causing virus -- information it said "was submitted by the Sputnik V vaccine developer itself." The decision to deny emergency use authorization for the vaccine, announced Monday, has blown up into an all-out international row. Sputnik V said earlier Thursday it was "undertaking a legal defamation proceeding in Brazil against Anvisa for knowingly spreading false and inaccurate information." "Anvisa made incorrect and misleading statements without having tested the actual Sputnik V vaccine," it tweeted. The regulator fired back defensively in a press conference. "Anvisa was accused of lying, of acting unethically, of disseminating fake news about replicating adenovirus," said the agency's director, Antonio Barra Torres. "We refute this grave accusation." bur-jhb/bfm