LAHORE, Pakistan — An exiled former prime minister, Nawaz Sharif, returned home to a hero’s welcome yesterday and called on President Musharraf to end emergency rule before elections, a fresh challenge to the American-backed leader.

“These [emergency] conditions are not conducive to free and fair elections,” Mr. Sharif told reporters at the airport after arriving from Saudi Arabia. “I think the constitution of Pakistan should be restored, and there should be rule of law.”

Mr. Sharif, the head of one of the country’s main opposition parties, said he had not negotiated his return with General Musharraf, who overthrew him in a 1999 coup. General Musharraf expelled Mr. Sharif when he first tried come back to Pakistan this year. “My return is not the result of any deal,” Mr. Sharif told reporters. “My life and death are for Pakistan.”

Thousands of frenzied supporters pushed past police barricades into the airport in this eastern city, carrying Mr. Sharif and his brother on their shoulders and cheering wildly as Mr. Sharif stood among them on a raised platform. An armored car carrying Mr. Sharif left the airport on a procession toward a shrine in the center of the city, surrounded by screaming supporters.

General Musharraf has grown increasingly unpopular since he declared a state of emergency on November 3, locking up thousands of opponents, purging the Supreme Court, and muzzling the press.

If Mr. Sharif and other opposition parties refuse to take part in parliamentary elections slated for January, it would undermine General Musharraf’s claim to be taking the country back toward democracy. Equally tricky for General Musharraf would be an alliance between Mr. Sharif and another recently returned prime minister, Benazir Bhutto.