Appearing at Lord Justice Leveson's inquiry into press and media ethics in London, Rhodri Davies QC said that phone hacking "was wrong, it was shameful, it should never have happened".
Davies said that News International now accepted that hacking "was not the work of a single rogue reporter", but he called on claims that 28 of its staff were involved to be "rechecked".
Yesterday, counsel to the inquiry, Robert Jay QC, told the high court that "at least 27 other News International employees" were named in the paperwork of private investigator Glenn Mulcaire, as well as jailed royal reporter Clive Goodman.
In total, Jay said that around 28 names are legible in the 11,000 pages of notes which police seized from Mulcaire, relating to a total of 2,266 taskings and the names of 5,795 potential victims.
The QC also said that evidence was emerging that hacking extended beyond the News of the World, as Mulcaire also wrote "The Sun" and a name relating to the "Daily Mirror" in his notes.
However, Davies said that Jay's statement had "occasioned some surprise on our side", according to media reports.
He said that News International was aware that five News of the World journalists were named among the notes seized from Mulcaire, including Goodman and four others, who were not named.
Lord Justice Leveson is examining the "culture, practices and ethics of the press" and considering the future regulation of the press following the phone hacking scandal that resulted in the closure of the News of the World in July.
Davies said that he could offer no guarantee that phone hacking at the News of the World had not continued after 2007, when Mulcaire and Goodman were jailed. But he denied that the illegal practice was a "thriving cottage industry" at the now defunct Sunday tabloid.
> News of the World private investigator Glenn Mulcaire 'was instructed to hack'
Davies told Lord Leveson that the News of the World had "managed to plumb the depths and heights" of journalism over the years - the heights being credible stories such as the exposure of cricket match-fixing, but the depths being the shocking revelations of phone hacking
He said that the company regarded the commissioning of a private investigator to operate surveillance on lawyers acting for phone hacking victims and select committee MPs as "wholly unacceptable".
But he told Leveson: "The inquiry should, we suggest, be somewhat wary of making recommendations designed to fight the last war rather than the next one."
Meanwhile, the BBC reports that a barrister for Associated Newspapers - publisher of the Daily Mail, Mail on Sunday, Evening Standard and London Metro - told the inquiry today that the newspaper publisher was not aware of any of its staff engaging in phone hacking.
> Over half of Brits lost faith in newspapers after phone hacking scandal