Private detectives have been and continue to be used occasionally by the BBC to help make its investigative programmes, the corporation's director-general has said.
Mark Thompson said the use of private investigators has always been done under the BBC's editorial guidelines and the control of programme editors involved.
The disclosure came after its Panorama programme earlier this month aired fresh hacking allegations against the News of the World, accusing one of the tabloid's executives of snooping through a former army spy's emails.
Former Irish edition editor Alex Marunchak used a private detective to illegally obtain private emails from former British army intelligence officer Ian Hurst in 2006, the programme claimed.
The top-selling Sunday tabloid, which has faced a slew of hacking claims, said it had received no evidence from the corporation to support the "serious allegations".
In an interview published today, Mr Thompson said that occasionally the corporation's projects "have done and do use" the services of investigators.
He told The Times: "Occasionally BBC investigative programmes have used and do use private investigators, always under the BBC's editorial guidelines and under the control of the editors of the programme involved.
"I don't think there's any suggestion that I can detect of any wrong-doing."
He added that it "feels like a bit of a smear" to suggest the BBC had done anything wrong in using outside investigators.
David Jordan, the BBC's director of editorial policy and standards, said he was not aware of any BBC programme using a private detective to hack private voicemails or other people's email accounts.
In a blog earlier this week, he said: "It is worth stressing that we are not aware of any BBC programme ever having commissioned a private detective to carry out this sort of illegal activity at any time in the past.
"It would be totally unacceptable and a serious breach of our editorial standards.
"But engaging private detectives to do things of this sort is very different from asking them to undertake lawful activity as part of an investigation in the public interest."
As an example, he said that consumer investigation programmes might use third parties to carry out surveillance to find out where they are so that they can confront them with allegations of wrong-doing.
"Usually we track down individuals we want to speak to ourselves. But in very hard cases we might employ the specialist skills of a private detective to help us find someone," he added.
"That may not be for suspected wrongdoing but could be to locate a witness to events which happened some time ago and who we are hoping will contribute to the programme."
News International has claimed repeatedly that only one of its journalists - former royal correspondent Clive Goodman - was involved in hacking.
Goodman and private investigator Glenn Mulcaire were jailed in 2007 after they admitted intercepting messages by using industry codes to access voicemails.
Scotland Yard reopened inquiries in January, with acting commissioner Tim Godwin pledging to leave "no stone unturned" during investigations into the actions of staff at the paper.
A BBC spokesman said: "The BBC does not make regular use of private investigators.
"In the rare event that it is necessary we would only do so on clear understanding that no illegal activity could ever be condoned.
"All third parties would also be expected to observe at all times the BBC's editorial guidelines on fairness and privacy."