Several large Swedish websites are suspected to have been knocked out temporarily after overload attacks.

The Turkish hacker group Türk Hack Team has claimed responsibility for the attacks, as revenge for Rasmus Paludan setting fire to a Koran outside the Turkish embassy in Stockholm.

"If you burn a Koran, we'll burn up your servers," the group writes on Twitter.

And now they are directing a new threat to Sweden.

Describes themselves as nationalists

SVT Nyheter gets hold of the person who claims to be the hacker group's spokesperson through social media.

The spokesperson describes them as a nationalist hacker group, but at the same time claims that the group has no connection to Turkish President Erdogan, who has said on several occasions that Sweden cannot expect any Turkish NATO support after the Koran burning.

The hacker group also claims that they have "sensitive personal data" belonging to Swedes.

“Our intelligence team has gained access to large amounts of data.

Other hacker groups have provided us with additional amounts of data.

If you desecrate the Koran one more time, then we will start spreading it," the spokesperson writes in an email to SVT Nyheter.

"Ideologically driven"

In an interview in SVT's Morgonstudion, Pontus Johnson, professor and one of Sweden's leading cyber security experts, described the Turkish hackers as "ideologically driven amateurs".

- Technical competence and often also time are required for successful hacking, and I am not convinced that Türk Hack Team has enough of these resources, he later told SVT Nyheter.

But what kind of "sensitive personal data" could they theoretically have access to?

And what harm could they do?

Watch the video above for Professor Pontus Johnson's response – and more background information on the hacker group.