The 57-year-old Rotterdammer arrested in the port city on Thursday morning in connection with a Danish and German terrorism investigation had close links with Hamas, the Telegraaf said. 

The man was looking for weapons to stage attacks on Jewish targets in Europe, the German public prosecution department told the paper. 

The name, named by the paper as Nazih R, had contact with the recently killed Hamas chief Khalil Hamed Al Kharraz, who was number two at Hamas’ armed unit, the German authorities said. 

The request to arrest Nazih R came from Berlin not Denmark as earlier thought, according to the Telegraaf. Three other people were arrested in Germany as part of the investigation, as were three in Denmark although the link between them is not yet clear.

The Israeli secret service Mossad and Israeli prime minister Benjamin Netanyahu said in a statement that the arrest of the seven “foiled an attack aimed at killing innocent citizens on European soil,” the Times of Israel reported.

According to the Danish authorities, the three arrested there had links to organized crime both in Denmark and abroad, including to a gang named Loyal To Familia, or LTF, Reuters reported.

Danish prime minister Mette Frederiksen told reporters on the fringes of the EU summit in Brussels the situation was “as serious as it gets” but did not give further details.

Two days ago the threat level in the Netherlands was raised to four, or substantial, which means there is a real likelihood of a terrorist attack taking place.

EU Home Affairs commissioner Ylva Johansson warned recently that Europe faces a “huge risk” of terrorist attacks during the holiday period because of fall out from the Hamas Israel war.