UK authorities made over 570,000 requests to view people's private texts, emails and phone records last year, leading to privacy campaigners calling for greater oversight in relation to requests.
The Interception of Communications Commissioner's report for 2012 revealed that mistakes made while using intercepted information led to six members of the public being wrongly detained or accused of a crime.
All these cases had involved the use of internet data. In a further error, police visited the wrong address while looking for a child who had threatened to harm themselves.
The report said authorities may make several requests for information in the course of a single investigation, so the total figure for data requests did not equate to the number of individuals or addresses targeted.
The Interception of Communications Commissioner's report said there were 3,372 intercept warrants issued in 2012, which allow the police and intelligence officers to acquire the full contents of emails, telephone calls or text messages.
There was a 16% rise in such requests when compared to 2011. Outgoing commissioner Sir Paul Kennedy said he was aware of 55 related "errors or breaches" involved in full intercepts.
These included officers not having been granted the necessary permission, the wrong data being obtained, and errors made when copying data.
Authorities also made 570,135 requests for information about who was involved in certain communications, when those communications were made and where they took place.
These requests can include the name of an email account holder and the time and date of a person's telephone calls. The report said there were another 979 mistakes made involving these kinds of requests too.
Sir Paul said that around 80% of the mistakes were the fault of public authorities, and that 20% were caused by the networks or service providers that provided phone and internet data.
In addition to the police and the intelligence services, local authorities could also ask for data, relating to areas like unpaid taxes, illegal waste dumping, and counterfeit goods.
The report said 160 local authorities across the UK made a total of 2,605 such requests.
All the requests for data are allowed under the Regulation of Investigatory Powers Act 2000.
Nick Pickles, director of privacy group Big Brother Watch, told the BBC: "The idea that one commissioner with a handful of staff can meaningfully scrutinise 570,000 surveillance requests is laughable."
"The commissioner continues to refuse to even say how many applications he inspected, which only reaffirms how unconvincing his assurances are."
Pickles added: "If the public are to have confidence that these powers are being used properly our entire surveillance regime, devised before Facebook even existed, is in need of a total overhaul to bring it in line with modern technology, and to ensure people's privacy is not intruded upon either without good reason or by mistake."