Actor Hugh Grant called for the second part of an inquiry to uncover the extent of illegal phone hacking after settling his damages claim against Mirror Group Newspapers at the High Court.
Speaking outside after a brief hearing, he said part two of the public inquiry into press standards, chaired by Sir Brian Leveson, should go ahead.
The star added: "This newspaper group has misled the public and its shareholders for many years; and it has let down its readers and its hard-working journalists.
"The public were not told the truth, the victims were not told the truth, the shareholders were not told the truth and the Leveson Inquiry was not told the truth.
"That is why the second part of the Leveson Inquiry must take place - to get to the truth and discover who broke the law and who lied about it."
Mr Grant was at the London court to hear his lawyer give details of the settlement at a hearing before Mr Justice Mann on Monday.
It is understood it involves payment of a six-figure sum, which he has donated to the campaigning group Hacked Off.
The judge also heard details of settlements against MGN by actor Ralf Little and Rupert Lowe, who was the executive chairman and joint managing director of Southampton Football Club between 1999 and 2006.
Both men received undisclosed damages payouts and apologies from MGN.
Former police officer and Crimewatch presenter Jacqui Hames settled her action against News Group Newspapers, publishers of the News of the World, receiving an apology and "substantial damages".
Anjlee Saigol, of Taylor Hampton Solicitors, told the judge: "Mr Grant brought this action in relation to alleged illegal misuses of his private information, obtained by hacking into his voicemails, as well as blagging and surveillance, committed by MGN's journalists at all three of its newspapers over, as MGN now accepts, many years."
She added: "Although Mr Grant now has some clarity as to the extent of MGN's unlawful activities in relation to him, one of his principal reasons for pursuing this case was to uncover and establish the wider truth about MGN's investigations into and knowledge of its unlawful activities before it finally admitted these practices in September 2014."
Detailing Mr Grant's case, Ms Saigol said that as "part of the settlement", MGN admitted that a number of senior employees "condoned, encouraged or actively turned a blind eye to the widespread culture of unlawful information-gathering activities" at its national newspapers.
She also said the company "actively sought to conceal its wrongdoing from its many victims of intrusion" and admitted intrusions into people's lives could have been prevented.
Alex Wilson, for MGN, said: "MGN accepts that the unlawful interception of voicemail messages and procurement of private information about Mr Grant and others should never have happened.
"MGN acknowledges that was morally wrong and deeply regrets the wrongful acts of its former employees which caused damage and distress to those affected, including Mr Grant."