Investigators from the Federal Prosecutor's office have travelled to South Africa to search for evidence of links with the country's former Apartheid regime.
It is the first time Swiss investigators have gone to South Africa since allegations of criminal activities between the two countries' intelligence services surfaced in 1999.
Hansjürg Wiedmer, a spokesman for the Federal Prosecutor's department, confirmed a report in the "Tages-Anzeiger" newspaper, stating that two investigators had been in South Africa for a week to examine whether any offences had been committed.
Wiedmer added that the pair had been granted access to documents and witnesses under an international judicial agreement.
Earlier this month, the House of Representatives rejected calls to set up an independent parliamentary commission after fresh allegations of apartheid-era collusion between the Swiss and South African secret services appeared last year.
At a court hearing in Pretoria last summer, Wouter Basson, the director of South Africa's covert chemical weapons programme during the apartheid era, alleged that Peter Regli, the former head of Switzerland's secret service, had helped him acquire 500 kg of the illegal drug, Mandrax, from Russia in 1992.
Regli, who was cleared by a parliamentary inquiry three years ago of any involvement in South Africa's covert weapons programme, has repeatedly denounced the allegations.
However, the Swiss government announced in November that a parliamentary committee would re-open investigations into the alleged affair. Committee members have been given authority to question witnesses and examine documents both at home and abroad.
The Swiss defence ministry is also conducting its own internal inquiry into whether Switzerland helped South Africa to acquire chemical weapons.
swissinfo with agencies
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