The final number of victims of the News of the World's phone-hacking operation is expected to be in the region of 800 people, Scotland Yard has said.

This is a fraction of the 5,800 names the police had previously identified from the notebooks of Glenn Mulcaire, the private investigator used by the now defunct Sunday tabloid.

The head of the Metropolitan police investigation into phone hacking said she was confident all those who had their phones hacked or were likely to have been victims of the illegal practice had now been contacted.

Sue Akers, a deputy assistant commissioner at the Met, told the Times: "We are confident we have personally contacted all the people who have been hacked or are likely to have been hacked. But there is a raft of people still to be spoken to who are potential targets, but are unlikely to have been hacked."

Scotland Yard said the number identified as of last Tuesday was 803 individuals including crime victims, celebrities, senior politicians and sports people.

A Met spokesman said it would be wrong to conclude that the remaining 5,000 names identified in Mulcaire's notebooks were not hacked.

"That is an assumption," she said. But the Times said that because of the lack of information about the remaining people, they were unlikely to have been hacked.

Mulcaire is known to have meticulously documented the name of the individual whose phone numbers he had been asked to get details about.

Some victims such as Sienna Miller told the Leveson inquiry that the Mulcaire files showed to her by police showed he had extensive details about her, including all the mobile numbers she had changed over three months, pin numbers for her voicemail and the password for her email that was later used to hack her computer in 2008.

The Met is expected to spend £4m per year on Operation Weeting and because of the scale of the investigation is seeking more resources to deal with the workload.