"The foreign ministry is in touch with the group," a ministry spokesman said. "Out of consideration for the interests of the abducted person, we cannot currently give any more information."
Security sources in the region told AFP on Sunday that the woman, Beatrice Stockly, had been snatched from the group that originally kidnapped her on April 15th by armed Islamists who wanted to free her.
A source in Timbuktu said Stockly had originally been in the hands of a private militia that wanted to sell her to Al-Qaeda in the Islamic Maghreb (AQIM).
Two sources in Timbuktu, speaking on condition of anonymity, said on Sunday the Islamist group Ansar Dine had battled the kidnappers for Stockly and were prepared to free her.
A separate source said Ansar Dine had "rejected an offer for mediation by a humanitarian group, saying they prefer to speak directly to the Swiss".
Stockly is in her 40s and was the last westerner still living in Timbuktu, having refused to leave after Ansar Dine and AQIM took control of the city on April 1st after a coup in the south that allowed rebels to capture the country's vast north.
Since seizing the fabled city, Ansar Dine has set about implementing sharia law.
AQIM, which has bases in the north of Mali, operates across the Sahel region.
Along with splinter group the Movement for Unity and Jihad in West Africa (MUJAO), it is currently holding 12 European and seven Algerian hostages.