The BBC spent £310,000 on private detectives over a six-year period, the Leveson Inquiry heard today.
The corporation once used investigator Steve Whittamore, who was later convicted of illegally accessing personal data, to check whether someone was on a particular flight.
On another occasion a BBC journalist commissioned a private detective to find out the owner of a car from its number plate, the hearing was told.
BBC director-general Mark Thompson told the press standards inquiry that the corporation's staff used investigators 232 times between January 2005 and July 2011 at a total cost of £310,000.
News accounted for 43 of these occasions, at a cost of £174,500, excluding the use of private security teams.
BBC Vision, which produces the corporation's TV programmes, was behind the remaining 189, spending about £133,000, in most cases for consumer shows.
Mr Thompson said these costs represented 0.011 per cent of the news budget and 0.002 per cent of the Vision budget over this period.
The inquiry heard there were two mentions of the BBC in the documents seized in the investigation into Whittamore's activities known as Operation Motorman.
In 2001 a current affairs journalist commissioned Whittamore to supply information about whether a paedophile was on a flight into Heathrow Airport.
The programme, which for other reasons was never broadcast, was looking at whether people with UK convictions for child sex offences could get jobs giving them access to children in other countries.
Mr Thompson said: "The request to try and find out whether this particular paedophile was on the aircraft, I would regard as being justified in the public interest."
He added that the Motorman papers also included a reference to "BBC wine blag", which appeared to be an attempt by a newspaper to discover the corporation's spending on alcohol.
Whittamore's Hampshire home was raided by investigators from the Information Commissioner's Office in March 2003. He was convicted of illegally accessing data and received a conditional discharge at London's Blackfriars Crown Court in April 2005.
A BBC journalist also used a private investigator to find out the owner of a car from its number plate after the vehicle was used by someone suspected of involvement in a serious criminal conspiracy, the inquiry heard.
David Barr, counsel to the inquiry, suggested that this involved accessing private details from the DVLA's vehicle registration database.
Mr Thompson replied: "There were many different ways in which this information could be obtained."
He added: "It seems to me that it is an example where the technique used was justified in the context of the public interest journalism that was involved."
The director-general said in most cases the BBC used private detectives to provide surveillance or security in support of journalists.
But sometimes investigators are commissioned to track down the subject of a programme so they can be given a right of reply.
The BBC places a very high importance on allowing people time to reply to allegations against them, sometimes giving them as long as 10 days in the case of a complex financial investigation, the hearing was told.
The inquiry heard that Mr Thompson commissioned a wide-ranging review of the BBC's editorial practices last July, covering phone hacking, "blagging" information, paying police and other public officials for information and the use of private detectives.
It found no evidence that any of the corporation's staff had hacked phones or made improper payments to police officers.
The BBC sometimes makes small payments to politicians and police officers for appearing on programmes like Crimewatch, the hearing was told.
Mr Thompson noted: "Occasionally a politician, or indeed anybody else, appears on an entertainment programme on the BBC or a comedy programme on the BBC. They might receive a fee."
Mr Thompson said BBC Radio 2's broadcast of Jonathan Ross and Russell Brand's lewd answering machine messages for Fawlty Towers actor Andrew Sachs was "a very serious lapse of editorial judgment".
The corporation added rules relating to intimidation and humiliation to its guidelines after the episode in 2008, the inquiry heard.
The director-general said "the probity, the integrity and the conviction" of BBC journalists was "not to be questioned".
"There are a lot of journalists in the organisation who could teach me a thing or two about journalistic standards," he said.
The BBC receives about 240,000 complaints a year, a typical one being that a viewer's programme was rescheduled because a sports match over-ran, the hearing was told.
Mr Thompson said he did not think the corporation had lost a defamation action in court for a decade, although it settles up to six cases a year outside court.
The director-general was asked about the BBC's decision to broadcast a Panorama documentary about alleged Fifa corruption despite calls to postpone it until after the decision was made about England's 2018 World Cup bid.
He said: "My response was we were right to pursue the investigation and I thought it would be wrong to adjust the scheduling or the character of the programme in any way.
"I wanted to stand behind Panorama's absolute right to do that investigation and to broadcast it as scheduled - which is what we did."
Mr Thompson said it was "quite desirable" that British newspapers were not as heavily regulated as broadcasters, which have a broader and more immediate reach.
"I think that this country in the end has benefited from having a range of media which are funded differently, constituted differently and have different objectives," he said.
He echoed comments to the inquiry last week by Times editor James Harding, who voiced fears that any new law underpinning press regulation could be easily made stronger by politicians at a later date to suppress newspapers.
Mr Thompson said: "Historically the BBC has argued against a statutory foundation, preferring instead the idea of royal charters given over 10-year periods, precisely to stop the risk of political change to its constitution in mid-flight."
Inquiry chairman Lord Justice Leveson observed: "The fact is that if that situation arose, there would be nothing to stop Parliament passing an Act tomorrow anyway."
The BBC director-general said there was a danger that the phone-hacking scandal gave the impression that all tabloid newspaper journalism was "bad or dishonest".
"That simply isn't the case, and I think that trying to keep objectivity about the range of journalism and about the quality of much of our newspaper journalism is an important part of the story as well," he said.