An estimated 10,000 Pakistanis have protested in Lahore over a Dutch politician's plans to hold a cartoon competition featuring caricatures of the Muslim Prophet Muhammad, with more mass protests expected in the coming days.

The protests on August 29 were organized by Tehreek-i-Labaik, an Islamist party that won an unexpectedly large number of votes in last month's general election, with some candidates campaigning on promises of punishment for crimes of blasphemy.

Physical depictions of Allah or the Prophet, even positive ones, are forbidden in Islam and considered deeply offensive. Pakistan's newly elected government has denounced the Dutch cartoon contest, calling it an attempt to defame Islam.

But Labaik party leader Khadim Hussain Rizvi said that is not enough and is calling for a break in diplomatic ties with the Netherlands.

He said he intends to take the protests that began in Lahore through the towns of Punjab Province to the capital Islamabad, where protesters plan to stage a sit-in to pressure Pakistan's new Prime Minister Imran Khan to cut diplomatic ties with the Netherlands.

"The Dutch ambassador should be immediately deported," Labaik spokesman Ejaz Ashrafi told Reuters. "We will only stop when the government meets this demand."

Pakistan has already complained to the Dutch government about the contest planned by Geert Wilders, a far-right Dutch lawmaker with a history of incendiary remarks about Islam. The event has the potential to upset Muslims not only in Pakistan but elsewhere around the world.

Wilders has said he intends to display the cartoons on the walls of his political party's room in parliament. He said he’s had "hundreds" of entries.

The Netherlands' Prime Minister Mark Rutte last week distanced his government from the cartoon competition, saying it "was not something I would do," while defending Wilders' right to freedom of speech.

Khan's office said on August 29 that Pakistan has registered a protest with the Dutch ambassador over the matter and will bring the matter before the United Nations.

"They don't understand how much they hurt us when they do such acts," Khan said on August 28, a day after the upper house of parliament condemned the planned cartoon competition.

Officials from the Punjab provincial government met with Labaik leaders in Lahore in a vain attempt to persuade them to call off their protest on August 29.

But emotions have been running high over the matter in Pakistan, where blasphemy is punishable by death and where the mere accusation of it can cause lynchings.

A former Pakistani cricketer, Khalid Latif, has offered a $28,000 reward for anyone who would "kill the Dutchmen" behind the cartoon contest.

On August 28, Dutch news reports suggested that a man who was detained there on suspicion of threatening to attack Wilders was a Pakistani national. Police said they detained a 26-year-old suspect who is likely to be arraigned on August 30.

Wilders has for years lived under constant security due to repeated death threats linked to his criticism of Islam.

Labaik led a major protest against the government last year, shutting down a main highway leading into Islamabad for nearly three weeks over a small change in wording in an electoral law that it contended amounted to blasphemy.

The ruling Pakistan Muslim League-Nawaz party at that time was forced to accept the resignation of Law and Justice Minister Zahid Hamid, who Labaik held responsible for the change, after seven people were killed and nearly 200 wounded in a failed attempt by police to disperse the protesters.

With reporting by AP, dpa, and Reuters