The Europol data leak was reportedly caused by a ex-employee who took some dossiers home.
Information on numerous international investigations into terrorism groups compiled by Europol was accidentally left online, unguarded by any password, a Dutch television programme reported on Wednesday.
Europol, which helps European Union national police organisations cooperate, could not immediately be reached for comment. The television programme Zembla cited the Europol's adjunct director Wil van Gemert as acknowledging the incident.
According the programme, the leak was caused by a former employee who took dossiers home, against Europol policy, and put them on a hard drive connected to the Internet without realising it was accessible to anyone.
Zembla did not republish the dossier, which it said contained information about 54 different police investigations, including the names and telephone numbers of suspects.
Van Gemert was quoted saying it did not appear that the dossier had been seen by anyone other than Zembla researchers, but he could not rule it out.
Privacy campaigner and Dutch Member of the European Parliament, Sophie In't Veld, tweeted: "Huge data leak. Will call for @EU_Commission and @Europol director to come and inform @Europarl_EN."
© Thomson Reuters 2016
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