According to the paper, the division of the UK's intelligence agency operations was responsible for 62% of wrong applications for communications data during the year.
Writing in Guardian Professional, government editor SA Mathieson quoted Sir Paul Kennedy, the UK communication commissioner's annual report as noting that MI5 wrongly collected subscriber data on 134 telephone numbers due to a software error.
"A spreadsheet formatting error caused the service to apply for data on the identity of telephone numbers ending in 000, rather than the actual last three digits" says the paper.
Sir Paul's report noted that the resulting data was destroyed, the formatting problem fixed, with numbers now checked manually before MI5 requests subscriber data from communications providers.
The Guardian asserts that MI5 also collated data on the histories of 927 internet connections, but without authorisation from a sufficiently senior officer, of GD3 rank or above.
"This was due to an 'incorrect setting on the system used by the Security Service,' according to Kennedy, although the requests themselves were necessary and proportionate", says the paper, adding that the spy agency has since corrected the setting on its systems.
Interestingly, Sir Paul's report said that public authorities submitted 552,550 requests for communications data during 2010, with that number increasing by about 5% a year.
The paper notes that almost two-thirds of requests for communications data, about communications rather than contents, were for subscriber data.
This was, says the paper, "usually part of an attempt to find the owner of a mobile phone. About a quarter of requests were for traffic data."