Six people have been arrested in the UK and are being quizzed over the now closed music site, OiNK.
Five men and one woman have been hauled in by Cleveland Police.
The arrests were made on 23 and 28 May, but police have only just released details.
Five men, aged between 19 and 33, and a 28-year-old woman have now been bailed "pending further inquiries".
A 24-year-old man from Middlesborough, who was arrested earlier on in the invesitgation, is due to answer bail on 1 July.
The website was shut down in October as part of an Interpol inquiry.
The arrests follow on from a 2-year investigation into the website by two music bodies representing labels in the UK - the International Federation of the Phonographic Industry (IFPI) and the British Phonographic Industry (BPI).
The investigation also led to raids in Amsterdam in October, where the website's servers were allegedly based.