The hackers, calling themselves NSHC, stole the names and email addresses of SVP supporters in the cyber attack, said tech website inside-it.ch.
Contacting the website by letter, the group said it had no intention of using the data, but simply wanted to show that Switzerland is vulnerable to cyber attacks and open a debate on the subject.
The SVP confirmed to daily 20 Minuten that it realized on Wednesday that it had been a victim of a cyber attack, however it could not yet confirm if any data had been stolen.
According to inside-it.ch, the same group claimed responsibility for a number of cyber attacks on commercial websites earlier this week.
The websites for Interdiscount, Swiss Federal Railways (SBB) and Microspot were all down between Saturday and Monday.
Melani, the Swiss information safety body, told 20 Minuten it knew nothing of the so-called NSHC, and it could not officially confirm the group's implication in the recent hackings.
Hackers who act like NSHC are known as ‘Grey Hats', because although they act illegally to break into websites, they do not do it with malicious intent but to bring awareness to security weaknesses.
In contrast, so-called ‘Black Hats' use hacking to blackmail their victims, as was the case earlier this week when a group called Armada threatened a number of banks with cyber attacks if they did not pay 10,000 francs, reported 20 Minutes.
However in that particular case Melani director Max Klaus doubted that the threat did actually come from the Armada group.
Speaking to 20 Minutes he said the group would normally launch an attack in advance to demonstrate what it is capable of.
“But no such demonstration has taken place on any of the banks in question,” he said.