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 of Sweden, were ordered to remain in custody for four weeks by a Danish court.

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.

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

In Stockholm, a court ordered Sahbi Zalouti, 37, held in detention on suspicion of helping prepare the attack. Zalouti, a Swedish citizen of Tunisian origin, turned his head away from reporters in the courtroom. His attorney said he "firmly denies" the charges against him.

Swedish newspapers reported that Zalouti was arrested in Pakistan in 2009 for traveling without the proper documents.

He told the Swedish tabloid Aftonbladet at the time that he had been in the country to meet other Muslims and spread information about Islam. He said he had lost his travel documents when his backpack was stolen and was released after serving a short prison sentence.

Western officials have long been concerned about citizens traveling to Pakistan for training in extremist camps.

Danish and Swedish police said the group, which they had been observing for months, planned a shooting rampage in the building where the Jyllands-Posten newspaper has its Copenhagen news desk. The Danish intelligence service said it seized a submachine gun, a silencer, and ammunition.

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 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.