Murdoch told News Corp staff in a memo on Wednesday that the company recently launched the probe as a "forward-looking review" to improve compliance with bribery laws.
The media tycoon told staff that the anti-corruption review was "not based on any suspicion of wrongdoing by any particular business unit or its personnel".
The memo described the review as focused on selected locations around the globe. One of these locations is London, where News International publishes the Sun, the Times and the Sunday Times. It also published the now-closed News of the World.
It is understood that News International's broad internal anti-corruption review began officially in July last year, when Tom Mockridge replaced Rebekah Brooks as chief executive.
The probe accelerated when Imogen Haddon took over as chief compliance officer at News International in March. News Corp also appointed two New York-based compliance officers to oversee company-wide procedures. Gerson Zweifach, ex-senior executive vice-president and general counsel, is News Corp chief compliance officer and Lisa Fleischman, former associate general counsel, is deputy compliance officer.
The Metropolitan police has arrested 14 current or former Sun journalists as part of its ongoing investigation into inappropriate payments to police and public officials.
Murdoch said in his memo to staff: "As you are all aware, our company has been under intense scrutiny in the United Kingdom. I assured parliament and the Leveson inquiry that we would move quickly and aggressively to redress wrongdoing, co-operate with law enforcement officials and strengthen our compliance and ethics programme company-wide. With the support of our board of directors, I am pleased to tell you that we have made progress on each of these important steps."
He added: "We have already strengthened and expanded our anti-bribery training programmes. To ensure the effectiveness of our entire compliance and ethics programme, we have recently initiated a review of anti-corruption controls in selected locations around the globe. The purpose of this review is to test our current internal controls and identify ways in which we can enhance them.
"Let me emphasise that the review is not based on any suspicion of wrongdoing by any particular business unit or its personnel. Rather, it is a forward-looking review based on our commitment to improve anti-corruption controls throughout the company."
Murdoch said the strengthening of News Corp's compliance procedures will take time and resources, but added that the cost of non-compliance are far more serious.