A co-founder of BitTorrent tracker The Pirate Bay has been arrested in Sweden over allegations he was involved in hacking a contractor to the country's tax authority.

Sweden's public prosecutions authority suspected Gottfrid Svartholm to be one of three involved in continued breaches of a core database held by contractor Logica over a two-year period.

The hacks, which began in 2010 and continued until April this year, reportedly involved accessing the database containing civic registration numbers for people with protected identities, with thousands of such numbers copied by the three over the breach period.