A Japanese policeman has been sacked after the personal information of thousands of people related to criminal investigations was leaked on to the internet from his computer.

The officer, who worked for the Metropolitan Police Department in Tokyo, accidentally revealed the details via peer-to-peer (P2P) file-sharing software on his PC.

He had allegedly installed the Winny file-sharing software on to his machine and was unaware that sensitive data was being made available to other users via the P2P network.

According to reports, the personal details of 12,000 people related to criminal investigations have been spread across the net from the officer’s computer and around 6,600 police documents have been compromised, including interrogation reports, victim statements, and classified locations of automatic licence plate readers.

Among the files was a list of the names, addresses and personal information concerning 400 members of the notorious criminal gang, Yamaguchi-gumi yakuza.