Zulmay Khan Uriakhail, the deputy police chief, said 12,000 police were deployed across the city and were searching all cars entering
He said about 3,000 people had arrived from outside the capital to attend.
Several top commanders who have been accused by some Afghans and rights activists of involvement in war crimes were expected to attend the rally.
Karzai has yet to comment publicly on the proposed amnesty. His spokesman has said the president would not sign anything that goes against