Mr Karzai has expressed frustration at the process after the recent assassinations of several key Afghan leaders.

US officials say Ms Clinton also wants to convince Afghans that Washington is committed to a long-term relationship with their country. The US is planning to withdraw troops and hand over security to the Afghans.

Her visit to Afghanistan was not announced until she arrived in Kabul late on October 19.

Burhanuddin Rabbani was a former Afghan president tasked with trying to reconcile the Taliban with Mr Karzai's US-backed government. He was killed last month by a suicide bomber posing as a Taliban envoy.

Ms Clinton met civic leaders at the US embassy in Kabul before her scheduled meeting with President Karzai.

She assured women's rights activists, education officials and politicians that their concerns were “being heard at the highest levels of the US government”.

Mrs Clinton has been a champion of women's rights in Afghanistan but activists fear that any deal with Islamist insurgents could undo advances made.