PARIS, Jan. 30 -- Cartoons in Danish and Norwegian newspapers depicting the prophet Muhammad in unflattering poses, including one in which he is portrayed as an apparent terrorist with a bomb in his turban, have triggered outrage among Muslims across the Middle East, sparking protests, economic boycotts and threats against the people, companies and countries involved.

The cartoons were published in September in a conservative, mass-circulation Danish daily, Jyllands-Posten, and were reprinted three weeks ago in Magazinet, a small evangelical Christian newspaper in Norway. But the reaction has been widespread, and fallout over the images reached new levels Monday, with the European Union backing Denmark in the dispute and warning that a boycott of Danish products -- already being felt by some companies -- would violate World Trade Organization rules.

Saudi Arabia has recalled its ambassador from Denmark and Libya has closed its embassy in Copenhagen, the Danish capital. Kuwait called the cartoons "despicable racism." Iran's foreign minister termed them "ridiculous and revolting."

The cartoons included one of the prophet as a crazed, knife-wielding Bedouin and another of him at the gates of heaven telling suicide bombers: "Stop. Stop. We have run out of virgins!" -- a reference to the belief of some Muslim extremists that male suicide bombers are rewarded in heaven with 72 virgins.

Islamic critics charged that the cartoons were a deliberate provocation and insult to their religion, designed to incite hatred and polarize people of different faiths. Defenders of the newspapers and artists said the 12 published cartoons simply were intended to highlight intolerance within Islam.

The controversy has pitted two newspapers championing what they say is the cause of free speech against Islam's prohibition of any artistic depiction of the prophet Muhammad, which is considered blasphemous, no matter how benign. The clash is being fueled by a wave of anti-immigrant sentiment in staunchly secular Denmark, where many express frustration that the country's 200,000 Muslim immigrants are resisting assimilation into Danish society.

"There's widespread skepticism toward immigration and integration efforts" because of a popular belief that "immigrants are here to take advantage of the Danish system," said Ulf Hedetoft, a political scientist at Aalborg University and director of Denmark's Academy for Migration Studies.

"People are inclined to see Islam and political extremism as two sides of the same coin," he said.

In a statement, the 57-nation Organization of the Islamic Conference has condemned "the printing of blasphemous and insulting caricatures of the Prophet Mohammed," saying it "falls into the trap set up by fundamentalists and fosters acts of revenge." Protesters across the Muslim world have burned Norwegian and Danish flags and issued sharp denunciations.

The controversy began in September, after an author in Denmark complained that he could not find an artist willing, under his own name, to illustrate a book about the prophet's life.

In response, Jyllands-Posten, the conservative daily, ran 12 cartoons by various staff artists depicting Muhammad. The paper explained that the project was meant to gauge the public's response.

In the Islamic world, it was swift and furious, but in Denmark, the majority backed the paper's right to print the cartoons. A recent poll showed that 62 percent of those surveyed said the paper should not apologize.

The tumult passed, but was reignited even more furiously when Magazinet, the evangelical Christian paper in Norway, reprinted the cartoons. The editor, Vebjoern Selbekk, wrote that he was "sick of the ongoing hidden erosion of the freedom of expression." He told the Reuters news agency that he had received 15 death threats and more than 1,000 hate letters.

The Danish Foreign Ministry late Sunday issued a statement warning its citizens in nine Middle Eastern countries and the Palestinian territories to "show extra vigilance" because of the "strong negative feelings" sparked by the uproar.

Meanwhile, a Denmark-based dairy group, Arla Foods -- with about $421 million in annual business in the Middle East and about 1,000 employees there, according to its Web site -- said sales had come to a "standstill" across the region.

The newspapers have issued explanations but have couched their apologies. "We are sorry if Muslims have been offended," Jyllands' editor in chief, Carsten Juste, told the Associated Press, adding that the newspapers' actions were "within the constitution, the Danish penal code and international convention. . . . It is not a dictatorship like Saudi Arabia that is going to dictate our editorial line here in Denmark."

Norway described the cartoons as "unfortunate and deplorable." Danish Prime Minister Anders Fogh Rasmussen has refused to apologize. In a recent speech, without mentioning the controversy, he denounced "any expression, action or indication that attempts to demonize groups of people on the basis of their religion or ethnic background." But he added that "freedom of speech is absolute. It is not negotiable."

"The question here is how far do you show sensitivity and self-control over issues without falling into self-censorship," said Medhi Mozaffari, a professor at Aarhus University in Denmark, who defended his government's stance not to apologize.

"It's unthinkable that the prime minister would make an apology," he said. "This is Islamists putting democracies on trial to see how far they can be pressured."

Special correspondent Marie Valla contributed to this report.