COPENHAGEN, Denmark (AP) — A Danish prosecutor said Friday that an investigation that led to the arrests of three suspects in Denmark last month on suspicion of plotting to carry out “an act of terror" was linked to Hamas, according to a local media report.

The case has been shrouded in secrecy and very few details have been revealed about it until now.

”The investigation has provided information that, according to the police, the case has links to Hamas,” prosecutor Anders Larsson said during a custody hearing before an appeals court according to broadcaster TV2. “That information is no longer necessary to keep secret.”

Larsson didn't provide any further details.

On Dec. 14, Danish police said that three people were arrested across Denmark, while a fourth person was detained in the Netherlands. The case coincided with an arrest in the Netherlands and several in Germany of alleged Hamas members.

The Danish and German announcements were issued separately. It was unclear how or if the arrests were connected and if they were the result of coordinated actions, or even possibly one operation spanning the continent.

The Danish case was shrouded in secrecy.

Larsson spoke inside the building housing the Eastern High Court, which was due to decide on an appeal whether the three should be remanded in custody.

Last month, officials in Copenhagen didn't provide any details beyond saying the arrests had “threads abroad” and were “related to criminal gangs,” singling out a gang called Loyal to Familia that had long been behind feuds, violence, robberies, extortion and drug sales in the Danish capital.

However, Flemming Drejer, the operative head of Denmark’s Security and Intelligence Service, cryptically said on Dec. 14 that the police had “a special focus” on Jewish institutions. He added that the arrests were carried out in “collaboration with our foreign partners” and that those arrested were part of “a network.”

Those arrested in Denmark can't be identified under a Danish court order.

Authorities in Germany said they too had arrested three suspected members of the Palestinian militant Hamas group who were allegedly planning attacks on Jewish institutions in Europe were arrested.

The authorities alleged the men “have been longstanding members of Hamas and have participated in Hamas operations abroad.” They said the suspect were “closely linked to the military branch’s leadership” of Hamas, considered a terrorist organization by the United States and the European Union.

In the Netherlands, police said that a 57-year-old Dutch man was arrested in the city of Rotterdam, based on a request from German authorities.