Her capture is the first in the area since the kidnap and murder of two French journalists late November 2013 in Kidal.
"Beatrice, a Swiss citizen, was kidnapped in her home in Timbuktu by gunmen," a Timbuktu government official told AFP.
A Malian security source said armed men had gone to her home yesterday evening, "knocked on the door, she opened, and they left with her."
In Bern, the Swiss foreign ministry said it was "aware of the apparent kidnapping of a Swiss woman in Mali" and was in contact with the local authorities, but refused any further details.
The social worker was said at the time to be the last Westerner living in the legendary desert city, which she refused to leave when it fell to Islamist Ansar Dine rebels on April 1.
Two weeks later, special forces from Burkina Faso swept into rebel-held northern Mali aboard a helicopter and whisked her to safety in a pre-arranged handover by Islamist rebels.
"I am offering you freedom chocolates," she told the officials, security personnel and an AFP journalist on the helicopter, after fumbling through her leather satchel and, with a beaming smile, producing chocolate.
Ansar Dine's 2012 assault on Timbuktu had been backed by fighters from Al-Qaeda's north Africa branch, Al-Qaeda in the Islamic Maghreb (AQIM).
At the time a loose alliance of Tuareg and Islamist rebels took advantage of the political chaos in Mali's capital that followed a March 22 army coup by capturing the country's vast desert north, including Timbuktu.
