According to the news, why has the senior police officer resigned?

A second senior police officer has resigned in Britain in connection with the scandal over phone hacking and alleged corruption in the Rupert Murdoch newspaper empire. Assistant Commissioner John Yates stood down 24 hours after his boss, Britain’s top police commander Paul Stephenson. Naomi Grimley reports.
    John Yates said his resignation was a matter of "deep regret", but the ongoing phone-hacking scandal was becoming a distraction from his job leading Scotland Yard’s counter-terrorism unit. He said he’d been a victim of some malicious gossip and speculation. Earlier, details had emerged of his links with a former News of the World journalist, who’d been hired as a media consultant for the Metropolitan Police. Meanwhile, David Cameron is leaving his tour of Africa early in order to deal with the ongoing crisis, and parliament is to delay its summer holiday too to discuss the matter further.