Afghan special forces have rescued a kidnapped Australian aid worker, officials said on Monday, four months after she was taken at gunpoint in the country's volatile east.

Katherine Jane Wilson, said to be aged around 60, is "safe and well", Australian Foreign Minister Julie Bishop said, without disclosing when she was released or who was behind her abduction.

Unidentified masked gunmen kidnapped Wilson from Jalalabad, near the border with Pakistan, in late April when she was visiting the city for a women's embroidery project.

"I confirm that Kerry Jane Wilson, who was abducted in Afghanistan in April this year, has been released, and she is now safe and well," Bishop said in a statement, without saying whether she is still in Afghanistan.

The minister, who has previously said Australia does not pay ransom for kidnappers, voiced relief for Wilson and her family but would not provide details of how she was freed.

Afghanistan's main intelligence agency, the National Directorate of Security, said Wilson was released in a "special operation", without offering details.

"As a result of our efforts, she has been safely released. Several suspects have been detained and our investigation is still going on," NDS said in a brief statement.

Wilson, a well-known aid worker in the country, ran a non-governmental organisation known as Zardozi, which promotes the work of Afghan artisans -- particularly women.

- Growing insecurity -

Following her abduction an Australian man was seized, along with an American colleague, in Kabul by gunmen wearing police uniforms.

The two foreigners, professors from the American University of Afghanistan, were pulled from their vehicle earlier this month after the kidnappers smashed the passenger side window and hauled them out.

Bishop said she "deeply appreciates" the support of Afghan authorities in facilitating Wilson's release.

But she added: "To protect those who remain captive or face the risk of kidnapping in Afghanistan and elsewhere, the government will not comment on the circumstances of Kerry Jane's release."

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The abductions underscore the growing dangers faced by foreigners in Afghanistan, plagued by Taliban and other militant groups.

Foreign tourists, including British, American and German nationals, came under Taliban fire earlier this month in a volatile district of Herat, leaving some of them wounded. They were safely evacuated to Kabul and were flown out of the country.

Aid workers in particular have increasingly been casualties of a surge in militant violence in recent years.

Judith D'Souza, a 40-year-old Indian employee of the Aga Khan Foundation, a prominent NGO that has long worked in Afghanistan, was abducted near her residence in the heart of Kabul on June 9. She was rescued in July.

The Afghan capital is infested with organised criminal gangs who stage kidnappings for ransom, often targeting foreigners and wealthy locals, and sometimes handing them over to insurgent groups.

The United States in May warned its citizens in Afghanistan of a "very high" kidnapping risk after an American narrowly escaped abduction in the heart of Kabul.