BRUSSELS (AP) — A leading member of the European Parliament said Friday that Russian authorities had barred her from entering the country despite having a valid diplomatic passport.

German MEP Rebecca Harms, a frequent critic of Russian President Vladimir Putin, said that border guards kept her for three hours at Moscow airport and told her she had been declared persona non grata. Harms, a co-president of Parliament’s pro-environment Greens caucus, took the next plane back to Brussels on Thursday after being refused entry.