The Danish police on Wednesday arrested four people suspected of planning to attack the Danish newspaper Jyllands-Posten that outraged many Muslims  by publishing cartoons of the Prophet Muhammad in 2005. A fifth person was arrested in Sweden.

Denmark's PET security police said the suspects had planned to enter a Copenhagen office block housing several newspapers including offices of the daily Jyllands-Posten and to "kill as many as possible of those around."

"On the basis of the investigation, it is the PET's assessment that the detainees were preparing a terror attack against a newspaper, which according to the PET's information was Jyllands-Posten," it said. "It is likewise the PET's view that the attack was due to be carried out in the coming days."

The Danish justice minister said the suspects had a "militant Islamist background" and that the attempted attack was the most serious terrorist plot in Denmark so far.

Links to International Terrorist Networks

The men arrested in Denmark are a 44-year-old Tunisian, a 29-year-old Lebanese citizen, a 26-year-old asylum-seeker from Iraq and a 30-year-old man whose identity has not yet been established, said PET chief Jakob Scharf. The man arrested in Stockholm was a 37-year-old Swede of Tunisian origin.

The four Danish arrests were made in the Copenhagen suburbs of Herlev and Greve and the items confiscated by police included a submachine gun with a silencer as well as ammunition. The detainees had links with international terrorist networks, Scharf said.

Swedish police said the suspects were not linked to a botched suicide bombing  in Stockholm two weeks ago in which only the bomber died. In that case an email -- thought to have come from the attacker -- was sent just before the attack, protesting against a Swedish artist who had also drawn cartoons of the Prophet Muhammad, as well as against Sweden's military presence in Afghanistan.

History of Attacks

Jyllands-Posten published 12 cartoons featuring the Prophet Muhammad in 2005, which devout Muslims regard as blasphemy. The case triggered demonstrations in Muslim countries in which more than 150 people were killed. One of the cartoonists, Kurt Westergaard, continues to face death threrats and has been attacked  several times.

According to information obtained by SPIEGEL ONLINE, the five-man cell had been under police surveillance and security forces only stepped in when they saw the danger of an imminent attack.

It is not clear whether the cell was operating independently or was steered by a terrorist group outside Denmark. Several of the men arrested are believed to have belonged to the radical Islamist scene in the Swedish capital Stockholm.

"Jyllandsposten is an important target for jihadist terrorists," Swedish terrorism analyst Magnus Ranstorp told SPIEGEL ONLINE. "Anyone who carries one out will immediately become a star in the scene."