Police said Fariba Ahmadi Kakar was abducted by armed men while travelling in the central province of Ghazni with her three daughters.

It is the first time a female MP has been snatched by insurgents.

Police said the kidnappers had demanded the release of four Taliban prisoners in exchange for Mrs Kakar.

Ms Kakar's children were later released in an operation involving Nato forces and Afghan intelligence - but she is said to be being held in a separate location.

The abduction marks a sinister milestone in violent attacks against prominent women in Afghanistan, says the BBC's Karen Allen in Kabul.

As Nato troops prepare to leave the country at the end of next year, there are very real concerns that limited freedoms won for Afghan women are starting to unravel, our correspondent adds.

Just last month, the most senior policewoman in southern Helmand province was shot dead on her way to work.

And last week, Afghan senator Rooh Gul and her husband survived an attack in Ghazni in which their daughter was killed.