Switzerland's public prosecutor said the arrests came after an operation by federal police on Thursday in five Swiss cantons.

No further details are currently available.  

Hundreds of Islamists were rounded up in Saudi Arabia after the 12 May attacks on expatriate housing compounds which killed 35 people.

About 200 people were also wounded in the attacks after nine attackers drove cars packed with explosives into the compounds and detonated them.

Swiss-US cooperation 

Another 17 people, most of them Arab expatriates, were killed in the bombing of another Riyadh housing complex on 8 November.

The attacks have been linked to Usama bin Ladin's al-Qaida network, although no conclusive proof has been provided. 

Meanwhile, the Swiss authorities have worked closely with the United States since the September 11 attacks.

They have been particularly scrutinising whether Switzerland's banking systems could have been used to fund so-called "terror" groups.