COPENHAGEN, Denmark -- An Iraqi asylum seeker accused of plotting a shooting attack on the Copenhagen office of a newspaper that published cartoons of the Prophet Muhammad was freed Thursday due to an apparent lack of evidence.

Three other suspects, residents in Sweden, were ordered to remain in custody for four weeks by a Danish court.

The four men were arrested in the Danish capital on Wednesday, while police in Stockholm arrested a Swedish citizen of Tunisian origin, suspected of being linked to the plot.

Danish and Swedish police said the group, which they had been observing for months, planned a shooting spree in the building where the Jyllands-Posten newspaper has its Copenhagen newsdesk.

Jakob Scharf, head of the Danish Security and Intelligence Service Scharf, described some of the suspects as "militant Islamists with relations to international terror networks." He said more arrests were possible.

Scharf said the assault was to have been carried out before this weekend, and could have been similar in strategy to the 2008 terrorist attack in Mumbai, India, that left 166 people dead

The latest arrests brought renewed attention to simmering anger at the newspaper, which has been the target of several attacks and threats since publishing 12 cartoons of Muhammad in 2005.

The right-leaning daily, one of Denmark´s largest, had asked Danish cartoonists to draw the prophet as a challenge to self-censorship after the author of a children´s book on religion said its illustrator demanded anonymity because he feared retaliation for a picture of the prophet.

Islamic law generally opposes any depiction of the prophet, even favorable ones, for fear it could lead to idolatry.

Kurt Westergaard, the artist who drew the most controversial of the cartoons - the prophet wearing a bomb-shaped turban - has also been attacked and threatened.

The cartoons turned this small Scandinavian nation into a target of Islamist groups seeking to carry out terror attacks and prompted violent anti-Danish protests in Muslim countries in 2006.

Under a court order, none of the suspects held in Denmark can be named. Police said they were Swedish residents - a 44-year-old Tunisian, a 29-year-old Lebanese-born man and a 30-year-old whose national origin was not released.

The men face preliminary charges of attempting to carry out an act of terrorism and possession of illegal weapons. The men pleaded not guilty and refused to speak in the closed-door hearing at the Glostrup City Court in the Danish capital.

Preliminary charges are a step short of formal charges, but if they are formally filed and they are convicted they could face life sentences.

A Danish intelligence official said the released Iraqi man remains a suspect but gave no other details and spoke on condition of anonymity because he was not authorized to speak to the press.

The Jyllands-Posten newspaper is part a media group that also includes two of Denmark´s biggest dailies, Politiken and tabloid Ekstra Bladet, a photo agency, three publishing houses and a bookstore.

Its Copenhagen newsroom is in a media group building that is protected by metal fences and guards at all entrances. Mail is scanned and newspaper staff need identity cards to enter the buildings and the various floors. Similar protection has been set up at its headquarters in another city.

As a consequence of the threats, cartoonist Westergaard and paper´s former culture editor Flemming Rose, who was in charge of the cartoon publication, have round-the-clock bodyguards and are transported in armored vehicles.

The Iraqi suspect´s younger brother said he had been released and was at home with his parents.

"My brother is innocent. He is being called a terrorist because he is a devout Muslim," Farooq Muhammed Salman told the AP. "I know that my brother has nothing to do with this."

Salman said his brother, who suffers from various ailments, rarely leaves the apartment where he lives with his parents.

Officials said the men arrived by car in Denmark late Tuesday or early Wednesday from Stockholm. Police, who had been watching the group´s movements for two months, followed the vehicle and arrested them Wednesday as they left an apartment in a Copenhagen suburb.

Police didn´t visibly increase patrolling on the streets of Copenhagen.

"We have found no reason to change anything in relation to our preparedness," Copenhagen police spokesman Rasmus Skovsgaard told the AP. (© 2010 The Associated Press 12/30/10)