BRUSSELS — Two Tunisians and a Dane were arrested in Denmark on Tuesday to prevent what the Danish police said would have been “a terror-related assassination” of one of 12 cartoonists behind caricatures of the Prophet Muhammad published in 2005 that provoked fury across the Muslim world.
But the authorities said that the Dane would probably be charged and released and that the two Tunisians would simply be expelled, raising questions about how much evidence had been gathered in the case.
The security service said the arrests had been made in raids in Aarhus, a city where Jyllands-Posten, the newspaper that commissioned and first printed the cartoons, has its offices.
The newspaper said the suspects had been planning to kill its cartoonist, Kurt Westergaard, 73. He drew one of the most incendiary of the cartoons, depicting Muhammad wearing a turban in the shape of a bomb with a burning fuse.
Jakob Scharf, the head of the Security and Intelligence Service, told reporters on Tuesday that the Danish suspect, 40 and of Moroccan origin, would probably be released after being charged under antiterrorism legislation, and that the two Tunisians would simply be expelled as threats to national security. None were publicly identified.
People familiar with the investigation said what appeared to be leniency might mean that the police had intervened suddenly, before they had enough evidence to justify more serious actions.
On Tuesday night, Mr. Scharf said a decision to release a suspect could be explained by the fact that Danish investigators did not want confidential material to become public in court. “Often the case would be that we have material we would not want to put forward in a court case,” he was quoted as saying by Jyllands-Posten.
The arrests have revived concerns that Denmark, a country of five million known for its tolerance, could again find itself on the front line of the culture clashes between Islam and the West. Danish investigators say they have foiled at least two terrorism plots since the cartoons were published in September 2005.
Prime Minister Anders Fogh Rasmussen said Tuesday that freedom of speech was under assault. “Unfortunately, there are in Denmark groups of extremists that do not accept and respect the basic principles on which the Danish democracy has been built,” he said.
But Imam Abdul Wahid Pedersen, a Danish covert to Islam who is prominent among Muslims in Denmark, cautioned that the arrests should not be used to make a scapegoat of the Muslim minority in the country, where a rightist anti-immigrant party is the third largest in Parliament.
Islam forbids even respectful depictions of Muhammad, to avoid idolatry. (Mmmm, not really. This is a more recent development.) The caricatures, which were reprinted by various Western publications, set off weeks of violent and sometimes deadly protests in Africa, Asia and the Middle East. Mobs burned Danish flags and attacked Danish diplomatic missions, and boycotts of Danish goods spread in some places to European products in general.
Mr. Westergaard said in a statement that he had been living in fear for his life.