British police have arrested Prime Minister David Cameron's former communications chief and a former editor as part of an investigation into alleged widespread phone hacking by the News of the World tabloid.

London's police department said it detained the former Cameron media advisor, Andy Coulson, on Friday for suspected corruption and conspiring to intercept communications.

Mr. Cameron hired the ex-chief editor of News of the World last year, but Coulson resigned in January as police started investigating new allegations of phone hacking at the newspaper. Coulson quit the newspaper in 2007 when two employees were briefly jailed for intercepting phone messages of the British royal household.

One of those employees, former royals editor Clive Goodman, was re-arrested Friday for suspected corruption. Police also searched the newsroom of a second tabloid, the Daily Star, where Goodman had worked since his release.

Mr. Cameron told a news conference that he gave Coulson a “second chance” to serve as media advisor after the former News of the World chief provided assurances of not having any knowledge of the phone hacking incidents. But, the prime minister admitted that his appointment of Coulson did not work out.

British media revealed this week that the investigation of News of the World has expanded to include allegations that it eavesdropped on voicemails sent to the phones of murdered schoolgirls, victims of terrorism and slain soldiers. Other accusations include paying bribes to police for information on stories.

The revelations triggered public outrage and forced News of the World parent company News Corporation to announce that the best-selling tabloid will shut down after publishing its next Sunday edition.

Mr. Cameron promised Friday that a judge will lead a full public inquiry into the scandal after police conclude the investigation. He also pledged to appoint an independent panel to draft new regulations for British news organizations, whom he accused of failing to properly regulate their own conduct.

The British prime minister said leaders of British political parties had long turned a “blind eye” to bad media practices in order to win the endorsements of newspapers.

Mr. Cameron said he heard reports that the chief executive of News Corp's British unit, News International, has offered to resign over the scandal. Chief executive Rebekah Brooks previously managed the News of the World when many of the alleged phone hacking incidents took place, although she denies knowing anything about them at the time.

Mr. Cameron said he would accept Brooks' resignation if it were up to him.