Zardari was to speak to mourners later Saturday.

Sher Mohammad, 23, was among many supporters who trekked hundreds of miles (kilometers) to pay respects. "She gave her life for the people of this country, so we can walk a few miles to pay homage to her dignity," said Mohammad, whose feet were swollen from the trip.

Police officer Tanveer Odho estimated between 150,000 to 200,000 turned out at the mausoleum Saturday. At United Nations headquarters in New York, Secretary-General Ban Ki-moon said Friday he hoped a UN commission would be established in the near future to investigate Bhutto's killing.

Bhutto's party and Zardari have demanded a U.N. probe, but have not followed up vague allegations they made after her death that forces linked to then-President Pervez Musharraf were involved.

Musharraf's government blamed Baitullah Mehsud, a Pakistani militant commander with reported links to al-Qaida, citing a communications intercept in which Mehsud allegedly congratulated some of his henchmen. A Mehsud spokesman has denied any involvement.

The United States also said Islamic extremists carried out the attack. The Security Council, the UN's most powerful body, must authorize any investigating commission.

"The secretary-general is hopeful that, with the progression of the discussions, the commission could be established in the near future," UN deputy spokeswoman Marie Okabe said.