The former head of news and current chief reporter of the News of the World have been arrested on suspicion of involvement in phone hacking, sources said.
Ian Edmondson, 42, and Neville Thurlbeck, 50, were held by Scotland Yard detectives when they attended separate police stations in south-west London by appointment this morning.
The pair were questioned on suspicion of conspiring to intercept communications and unlawfully intercepting voicemail messages.
These are the first arrests since the Metropolitan Police reopened its inquiry into claims that staff at the top-selling Sunday newspaper hacked into the answerphone messages of celebrities, politicians and Royals.
Scotland Yard has endured a torrent of criticism over its handling of the original case, which led to the conviction of the News of the World's royal editor, Clive Goodman, and private investigator Glenn Mulcaire in 2007.
In January the force launched a fresh investigation, codenamed Operation Weeting, after receiving "significant new information" from the paper's publisher, News International.
The decision came amid a steady flow of new allegations about the practice of intercepting the mobile phone messages of high-profile public figures, said to range from actress Sienna Miller to former prime minister Gordon Brown.
Former News of the World editor Andy Coulson resigned as Prime Minister David Cameron's director of communications in January after admitting that the drip-drip of claims about illegal eavesdropping under his command was making his job impossible.
The News of the World sacked Edmondson from his job as assistant editor (news) days later after evidence emerged apparently linking him to phone hacking.
Scotland Yard refused to give any more information about the inquiry, saying: "The Operation Weeting team is conducting the new investigation into phone hacking.
"It would be inappropriate to discuss any further details regarding this case at this time."
Edmondson's solicitor, Eddie Parladorio, said: "I can confirm that Mr Edmondson was arrested today. He attended voluntarily at the police station. Other than that I have no comment."
Mr Parladorio also stressed that Edmondson has not been charged with any offence.
The News of The World declined to make an immediate comment on the arrests.
In 2009 a journalist for The Guardian alleged in evidence to the Commons Culture, Media and Sport Committee that Thurlbeck had received transcripts of intercepted calls.
The MPs were shown an email apparently sent to Mulcaire by a junior News of the World reporter in 2005 which stated: "This is the transcript for Neville."
The email included a typed record of voicemail messages exchanged between Professional Footballers' Association boss Gordon Taylor and his legal adviser.
Police were expected to search the homes of Edmondson and Thurlbeck today before releasing them, The Guardian reported.
News International later said in a statement: "In January, News International voluntarily approached the Met Police and provided information that led to the opening of the current police investigation.
"News International terminated the employment of the assistant editor (news) of the News of the World at the same time.
"News International has consistently reiterated that it will not tolerate wrong-doing and is committed to acting on evidence.
"We continue to co-operate fully with the ongoing police investigation."