A Swedish hacker who uncovered a security flaw in an email system used by embassies around the world has been arrested.

Security consultant Dan Egerstad was apprehended at his apartment by members of the Swedish Security Police and Swedish National Crime force.

Several computers, CDs and portable hard drives were removed from his home for examination.

Egerstad originally warned the embassies and government agencies that their email accounts could have been hacked.

When the warnings went unheeded Egerstad posted log-in information for more than 100 email accounts at on his Derangedsecurity.com website.

However, his investigation had actually uncovered 1,000 email accounts that could easily be hacked.

The consultant said that he was released from police custody after two hours of questioning and that no charges were filed.

"I got a couple of police IDs in my face while being told that they are taking me in for questioning," he told the Sydney Morning Herald.

"They broke my wardrobe, shorted my electricity, pulled out my speakers, phone and other cables having nothing to do with this and touched my bookkeeping which they had no right to do."