The woman was taken in the city of Jalalabad, close to the border with Pakistan, on Thursday, a government official in the area told AFP.
"She visited the city of Jalalabad for a women's embroidery project," said Ataullah Khogyani, a spokesman for the governor of Nangarhar province, of which Jalalabad is the capital.
"And unknown masked gunmen abducted her from Police District 2 of Jalalabad city."
He declined to give further details about her nationality but the Australian Broadcasting Corporation said she was an Australian from the western city of Perth.
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Foreign Minister Julie Bishop was quoted by the broadcaster as saying the government was liaising with Afghan authorities to find out more.
"We are in close contact with the family, we are working with Afghan authorities but at this stage there are still a number of matters that need to be confirmed before I can say anything more publicly about it," she said.
According to reports, the woman used to work with the Danish Committee for Aid to Refugees, an NGO that has been in Afghanistan since 1984.