About 25,000 people — some chanting "Death to America!" — rallied against the Prophet Muhammad caricatures in Pakistan's largest city Sunday, but police prevented a rally in the eastern city of Lahore by arresting the religious ringleader and detaining scores of supporters.

In Karachi, Pakistan's largest city and economic hub, where the provincial government has not banned such rallies, protesters also chanted "Down with the blasphemer!" and "End diplomatic ties with European countries!" No violence was reported.

About 25,000 people joined the downtown rally organized by Tahafuz-e-Khatm-e-Nabuwat, a Sunni Muslim religious group, said Shaukat Shah, a Karachi police officer.

The protest was the biggest in the port city since 40,000 rallied there Feb. 16 against the cartoons, which first appeared in a Danish newspaper in September but have been reprinted across Europe since.

In Lahore, clerics, opposition lawmakers and religious school administrators were among 150 people arrested or detained without charge Saturday and Sunday in a bid to thwart the illegal protest, police official Amir Zulfiqar said.

Pakistan banned such rallies in Lahore after several demonstrations turned deadly.

Police blocked all streets leading to a central Lahore mall where the protest was to be held. Some 15,000 policemen and 3,000 paramilitary troops were deployed in the city, guarding major traffic intersections, government buildings, mosques and foreign consulates, Lahore police chief Khawaja Khalid Farooq said.

Qazi Hussain Ahmed, a leader of a coalition of six radical Islamic parties, attempted to lead the rally but was taken away in a police vehicle after trying to break through a barricade, Zulfiqar said.

Nearly 100 of Ahmed's supporters chanted "Punishment for insulting the Prophet is death!" as they stood near the police blockade. There was no violence.

Parliamentary opposition leader Maulana Fazlur Rahman, who was prevented by police from boarding a flight to Lahore from Islamabad, vowed that the protests would continue.

"By arresting religious and political workers, the government displayed a dictatorial attitude which is condemnable," Rahman said.

"The government has shattered democratic values and by its steps it has strengthened those forces which have insulted the Prophet."

Protests targeting President Gen. Pervez Musharraf, the United States and the caricatures are scheduled for March 3 — a day before President Bush visits Islamabad.

Police also detained former cricket great Imran Khan, a lawmaker who now leads the Movement for Justice party, and 10 of his supporters near the venue of the planned rally, Zulfiqar said.

The prophet drawings have ignited violent protests across the Muslim world that have killed at least 45 people. Muslims have denounced the drawings — one of which shows a prophet with a turban shaped like a bomb with a lit fuse — as offensive to their religion.

Muslims consider any physical representation of Islam's prophet blasphemous.

The caricatures were first published by a Danish newspaper in September, then reprinted by other Western media, mostly in Europe but by some U.S. outlets, in the name of free speech and news value.

In Hong Kong, about 1,000 Muslims staged a peaceful rally in a downtown park Sunday.

"Any insults to the prophets will hurt Muslims," read placards held by some of the protesters. "Don't abuse the freedom of speech."

"I cannot describe how hurt I feel. The Prophet Muhammad is not only the prophet we follow, but he is dearer to us than our own selves," said Wael Ibrahim, an Egyptian sales manager who lives in the city of Shenzhen, across the border in mainland China.

In Malaysia, Prime Minister Abdullah Ahmad Badawi said he had ordered the suspension of a third newspaper that published a photograph showing the cartoons.

The Berita Petang Sarawak, the only Chinese-language evening daily on Borneo island, will be banned from publishing for two weeks, Abdullah said.

The government earlier ordered the suspensions of the English-language Sarawak Tribune and Chinese-language Guang Ming newspapers for reproducing the cartoons.