Phone hacking investigations could last another three years, costing £40m and investigating 1,000 victims, Scotland Yard has confirmed - but just 13 people have been charged.

Sue Akers, the Metropolitan police officer responsible for three investigations into wrongdoing by journalists, including those alleged to have accessed the voicemails of celebrities, politicians, crime victims and public figures, appears in front of the Commons home affair select committee on Tuesday.

She said the police had contacted more than 4,700 potential victims, and around 1,069 were likely to have been hacked.

phonehacking inquiries

Rebekah Brooks, former chief executive of News International, is one of those charged under Operation Weeting

Akers will retire next month, handing over the investigations for the next three years to deputy assistant commissioner Stephen Kavanagh, who will oversee Operation Weeting into phone hacking, Operation Elveden, illegal payments to public officials and police officers, and Operation Tuleta which will investigate computer hacks.

Some of the £40m Scotland Yard have budgeted includes legal fees for representation at the Leveson inquiry.

More than 180 staff are working on the three investigations. Akers said she would now be prioritising getting cases into court.

"An exit strategy is one of the most difficult issues. In terms of the phone hacking, it's perhaps easier to see an end because we now have people charged. That needs to take its course through the courts.

"In terms of the corrupt payments, that very much depends on the co-operation of the papers. If we're uncovering corrupt police officers we feel that we should continue to do that.

"There is an enormous amount of money being spent on this, a lot of police resource and post-Olympics we're going to be in very tight financial times."

There have been 25 arrests related to Operation Weeting, 43 in relation to Operation Elveden and 11 linked to Operation Tuleta, so far.

Akers said some victims have not been reached by police. "We're dealing with material that is six years old, so lots of people don't have the same telephone numbers, people move on."