KABUL - US Secretary of State Hillary Clinton arrived in the Afghan capital of Kabul on Saturday morning for an unannounced visit, an Afghan official said.

Clinton made the surprise visit one day before a key conference on the insurgency-hit country to be held in Tokyo, Japan on Sunday.

The top US diplomat will meet Afghan President Hamid Karzai later Saturday, the official added.

Delegates from some 70 nations and international agencies are expected to attend the one-day Tokyo conference on Afghanistan to review the achievements in the past decade and chalk out a new roadmap for the war-torn country, helping it stand on its own feet following the retreat of NATO-led troops after 2014.

UN chief Ban Ki-moon will also attend the conference.

Afghan President Karzai has said recently that his war-torn country expects the conference to pledge $3.9 billion a year for 10 years after 2014 when all foreign combat troops leave Afghanistan.