David Cameron today pledged a “robust” inquiry into illegal press practices and police failures in the wake of the phone-hacking scandal leading to a new system of press regulation.

The Prime Minister announced that Lord Justice Leveson, who as a barrister prosecuted serial killer Rose West, would lead a powerful probe that will be able to summon newspaper owners, reporters and police to give evidence in public.

The inquiry will take place in two stages, with a review of “culture, practices, and ethics of the press” beginning almost immediately.

It will cover links between journalists, politicians and the police, failures in the “policy and regulation framework”, and why action was not taken on previous allegations of media misconduct.

Within 12 months the inquiry will produce recommendations on a new policy and regulatory regime, including how best to deal with concerns about media ownership.

The terms of reference appear to cast further doubt over the future of the Press Complaints Commission, whichMr Cameron last week branded “ineffective,” “lacking in rigour” and “institutionally conflicted.”

The timing of the second stage, examining previous “unlawful and improper conduct” at the News of the World and other newspapers and how it was handled by the authorities, will depend on the “ongoing criminal proceedings”.

The judge has been instructed to consider “the way in which the police investigated allegations of unlawful conduct by persons within or connected with News International, and the review by the Metropolitan Police of their initial investigation”.

He will also look at the “extent to which the police received corrupt payments or were otherwise complicit in such misconduct or in suppressing its proper investigation and how this was allowed to happen”.

Mr Cameron said:  “No one should be in any doubt of our intention to get to the bottom of the truth and learn the lessons for the future.”

Lord Leveson said:  “The Inquiry must balance the desire for a robustly free press with the rights of the individual while, at the same time, ensuring that critical relationships between the press, Parliament, the Government and the police are maintained.

“The press provides an essential check on all aspects of public life. That is why any failure within the media affects all of us. At the heart of this Inquiry, therefore, may be one simple question: who guards the guardians?”

The PCC said in a statement:  “Like the Prime Minister, the PCC remains committed to the establishment of a more effective system, one that supports appropriate freedoms, but demands the highest ethical standards.

“We look forward to contributing to the work of Lord Justice Leveson.”