The eccentric mayor of Kiev, who mysteriously vanished from Ukraine and has not been spotted in public for months, has reappeared in Israel on "an unofficial holiday", a report said. Leonid Chernovetsky, who bewildered Ukrainians with his bizarre antics in office and still officially retains his post, was discovered by Ukrainian television channel 1+1 in an elite district of Tel Aviv. Its crew managed to gain access to his apartment and have a brief exchange with the mayor who expressed amazement that they had found him. "How did you get here?" he asked. "I am not giving an interview. I am on an unofficial holiday," he said in the report shown late on Wednesday. Ukraine's media has been buzzing for days with allegations that Chernovetsky has since 1994 had double Ukrainian and Israeli citizenship. He told the reporters he denied the allegations. Channel 1+1 managed to shoot mostly upside-down footage of Chernovetsky's apartment with a hidden camera and brief images of the mayor himself in a pair of shorts before being thrown out. Criticized for his management of the city of three million, the mayor was stripped of most of his powers by President Viktor Yanukovych last November. Kiev is now run by city administration head Olexander Popov. But to the embarrassment of many Kievans, Chernovetsky remains their official mayor. Nicknamed "Lyonya Kosmos" for his spaced-out eccentricities, the mayor has been accused of insanity by opponents. He once held a press conference by a pool while wearing swimming trunks, to prove his physical and mental health. However the administration of Yanukovych -- which is making great play of an anti-corruption crackdown -- made clear it found the allegations of dual nationality no laughing matter. "Mr Chernovetsky must turn to the Israeli authorities and ask for an official document to prove whether or not he is an Israeli citizen," the president's advisor Anna German told Channel 5. "If the truth is on his side then he needs to do everything to clear up the insinuations," she added.