Russia‘s interior ministry has threatened former Moscow mayor Yuri Luzhkov with reprisals if he fails to show up for questioning on an alleged $500m (£310m) bank fraud. Friday’s warning to Luzhkov, who lost his job a year ago after 18 years, follows his stinging attacks on the Kremlin. Luzhkov said the case was political payback for his criticism of the president, Dmitry Medvedev, and he would return from abroad to prove his innocence. The ministry postponed Friday’s questioning, but signalled it could issue an arrest warrant if he did not show for interrogation as a witness. The ministry made a similar warning to Luzhkov’s billionaire wife, Yelena Baturina, saying she had ignored previous summons.