By Renju Jose SYDNEY (Reuters) -Australia on Tuesday imposed cyber sanctions on a Russian man for his role in the breach at insurer Medibank, one of the country’s biggest data thefts which impacted about 10 million customers. Reports of cybercrime in Australia have spiked over recent years with several companies disclosing hacks, prompting the government last year to overhaul its cyber security rules and set up an agency to help coordinate responses. Targeted financial sanctions and a travel ban have been imposed on Russian citizen Aleksandr Ermakov after Australian authorities linked him to t…