There were more apologies from Rupert Murdoch's media group News International on Sunday as it struggled to win back readers' and investors' confidence shaken by the phone hacking scandal.

A day after Mr. Murdoch issued a signed public apology admitting “serious wrongdoing,” the News International on Sunday took out another advertisement in leading newspapers vowing to punish the “wrongdoers.”

Titled, “Putting right what's gone wrong,” it offered “full cooperation with the police” and said: “We will not tolerate wrongdoing and will act on any evidence that comes to light.”

“It may take some time for us to rebuild trust and confidence, but we are determined to live up to the expectations of our readers, colleagues and partners,” the advertisement said, dramatically declaring that there “should be no place to hide” for those responsible for failing to “uphold the values of decency and the rule of law.”

Meanwhile, the arrest of Rebekah Brooks, the former chief executive of News International, was seen as a personal blow to Mr. Murdoch and damaging to his companies, which have seen their shares fall in recent days. The timing of her arrest came as a surprise with News International sources being reported as saying that they had no prior inkling.

Critics described her arrest as an attempt by the police to deflect attention from the controversy over their own role in the hacking row. The family of Milly Dowler, the murdered teenaged schoolgirl whose phone was hacked by News of the World journalists, said the arrest “stinks.”

Labour MP Chris Bryant called the timings of the arrest “odd,” coming as it did two days before Ms. Brooks was to appear before the House of Commons media committee to answer questions about her role in the scandal.

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