Police have launched a fresh investigation into phone hacking after receiving "significant new information", Scotland Yard has said.
The information relates to hacking at the News of the World (NoW), which led to its royal editor being jailed.
The BBC has learned the paper sacked its head of news, Ian Edmondson, on Tuesday following an internal inquiry.
A source said a trawl of his e-mails had found "highly damaging evidence" that had been passed to the police.
A NoW spokeswoman later confirmed it had sacked Mr Edmondson and said it would take "swift and decisive action when we have proof of wrongdoing".
Mr Edmondson was suspended from active duties last month after he was identified in court documents as having instructed private investigator Glenn Mulcaire to access phone messages.
Mulcaire was jailed for six months in January 2007 alongside royal editor Clive Goodman, who was sentenced to four months, for hacking into the mobile phones of royal aides.
BBC business editor Robert Peston said it was information about Mr Edmondson that formed the basis of the fresh police inquiry.
A source at News International, which owns the NoW, told the BBC: "We have decided to root out and hunt down anyone connected with this practice. We are determined to end this."
The source insisted that no other newspaper executive, present or former, was implicated in the new evidence, but BBC home affairs correspondent Tom Symonds said that may not be the case.
"I've been told by two sources that Mr Edmondson has evidence himself that might implicate other senior people at the News of the World, so clearly this has opened a whole can of worms," he said.
The new inquiry follows the resignation last week of Prime Minister David Cameron's official spokesman Andy Coulson, who said the media storm surrounding ongoing hacking claims had distracted him from doing his job properly.
Mr Coulson edited the News of the World from 2003 to 2007 and resigned following the convictions of Goodman and Mulcaire.
However, he has always denied having any knowledge of hacking, and a source close to him has told the BBC he is not implicated in any way by the new evidence that has come to light.
Mr Cameron's spokeswoman said the new inquiry had come as a "complete surprise" to him.
She also said the prime minister had not discussed the issue of phone hacking when he had had a private dinner with News Corp boss James Murdoch and News International chief executive Rebekah Brooks over Christmas.
A number of public figures have launched civil legal actions against both the newspaper and the police amid allegations the practice of phone hacking was widespread.
Politicians from both government and opposition have also demanded the police investigate.
Labour MP Chris Bryant, who believes he may have had his phone hacked and is seeking a judicial review against the police over their handling of information, welcomed the new investigation.
He said: "It just goes to show that the Met never did a full or proper investigation in the first place and that they completely failed to follow every avenue of investigation.
"It is a scandal that it is only through the civil actions that people are bringing that the Met are being forced to act and we are beginning to see the full scale of what went on."
Meanwhile, former MP Paul Marsden has said he may take legal action against newspaper group Trinity Mirror over alleged phone hacking in 2003. The group said its journalists worked within the law.
The new inquiry will be moved from the Met Police's counter terrorism command to the specialist crime directorate.
It follows an earlier inquiry led by Assistant Met Police Commissioner John Yates which decided there would be no further investigation.