ATHENS (Reuters) - Athens turned down a request by Austrian Interior Minister Johanna Mikl-Leitner to visit Greece next week amid a row between the two EU members over Vienna's moves to restrict the flow of refugees, a Greek Foreign Ministry official said. Greece on Thursday recalled its ambassador to Austria in anger over the border closures and has threatened to block European Union decision-making unless the bloc comes up with concerted action to deal with the migrant crisis. (Reporting by George Georgiopoulos; Editing by Janet Lawrence)