Telephone numbers of relatives of dead military personnel have been found in files amassed by a detective employed by a Sunday tabloid newspaper, say reports.
It is unclear whether any of those telephones had been hacked. A report in Daily Telegraph said on Thursday's without identifying the source of its information.
The relatives of some soldiers said that they have not been contacted by police, but that a newspaper had asked them about possible hacking, an AP report said.
The News of the World, the newspaper which is the focus of a criminal investigation, issued a statement saying it would be absolutely appalled and horrified if there was any truth in the allegation, said the report.