Detectives are investigating a rape threat against Cheryl Cole in an answer phone message left on Dermot O'Leary's mobile phone.
The X Factor presenter was believed to have raised the alarm after picking up the threat on his voicemail left by an unknown caller.
A City of London Police spokesman confirmed an investigation had been launched into an "offensive message".
He said: "We are investigating claims of an offensive message being left on a mobile telephone. It follows a complaint from a member of the public."
Cole has been alerted to the threat, according to the Sun.
The singer was appearing on Fearne Cotton's Radio 1 show on Tuesday morning.
O'Leary, 36, joined the ITV show in 2007 - a year before the Girls Aloud star's arrival as judge.
The singer announced last month that she and her footballer husband Ashley Cole were splitting following reports that the England and Chelsea star had been repeatedly unfaithful.
Earlier this month, Cole, 26, was forced to pull out of a string of singing appearances after being struck down with a bout of bronchitis.
Security for The X Factor judges was apparently increased in 2008 after a tracking device was put into Simon Cowell's car.
