Dutch police arrested seven men Thursday suspected of plotting to carry out a "major terrorist attack" at a public event using explosive belts and an AK-47 assault rifle, the public prosecutor's office said.

"Police arrested seven men on Thursday... suspected of being at a very advanced stage of preparation for a major terrorist attack in the Netherlands," it said in a statement, adding one of the suspects had wanted to kill "many victims".

Prosecutors and investigators were "convinced that a terrorist attack was prevented" as a result of the arrests in the cities of Arnhem and Weert which followed a months-long police operation.

Officers had placed a group of people under surveillance, a central figure being a 34-year-old man of Iraqi origin convicted in 2017 of attempting to reach territory controlled by the jihadist Islamic State group, the statement added.

Those arrested by elite special anti-terrorist police teams with helicopter support ranged in age from 21 to 34.

The suspects came from Arnhem, the port city of Rotterdam and villages close to those two cities. Two others in the group also had convictions related to attempts to travel to Iraq or Syria.

"One of the men from Arnhem wanted to commit an attack with a group at a major event in the Netherlands and kill many victims, according to the Dutch Intelligence Service (AIVD)," the prosecutor's office said.

Police had yet to identify the target of the planned attack which the prosecutor's office said was to have included a separate car bombing.

The suspects, who investigators said said were in possession of small arms when they were detained, are expected to appear in court in Rotterdam on Friday.

"They were seeking AK-47 assault rifles, grenades, explosive belts and raw materials with which to make other bombs," investigators said.