Former News of the World journalists Andy Coulson and Clive Goodman will face a retrial on charges of conspiracy to commit misconduct in a public office, a London court ruled.
Coulson, a former News of the World editor and ex-Downing Street communications chief, was convicted last week of conspiracy to hack phones between 2000 and 2006.
But the jury was not able to reach a decision on two charges each against both for allegedly conspiring to commit misconduct in a public office.
Both Coulson and Goodman, the paper's former royal editor, have pleaded not guilty.
Another of Rupert Murdoch's former newspaper chiefs, Rebekah Brooks, was unanimously cleared of all charges last week after the eight-month trial at the Old Bailey court.
Public and political outrage over the hacking revelations led to the closure of the 168-year-old News of the World paper and the setting up of a public inquiry to examine journalistic ethics, known as the Leveson Inquiry, as well as a police investigation.
Coulson resigned as News of the World editor in 2007 after Goodman and a private investigator, Glenn Mulcaire, were jailed for hacking into voice-mail messages left for royal aides.
Coulson denied any wrongdoing and later became Prime Minister David Cameron's director of communications. The former editor resigned from his Downing Street position in 2011 as coverage of the phone hacking scandal broadened.