The trial of six men said to have been planning a major terrorist attack in the Netherlands began in Rotterdam on Wednesday.

The six were arrested after a major police undercover operation in September 2018 but the man police claim is the ringleader has accused the authorities of entrapment.

The investigation began into 34-year-old Hardi N, an Iraqi national, following a tip-off from the AIVD security service in early 2018.

At the time, the police said a ‘major terrorist attack’ had been averted, although details about what the gang were planning to do were thin.

‘The plan may have involved jackets packed with explosives and Kalashnikovs at an event and a car bomb elsewhere. The investigation into the exact target is still ongoing,’ the public prosecution department said at the time.

In total, seven people were arrested. They ranged in age from 21 to 34 and three of them, including Hardi, had previous convictions for attempting to join IS in Syria. One was later released, but the remaining six have been held in custody for almost two years.

In January 2019, photos showing the group of suspected terrorists wearing bomb vests and waving Kalashnikov rifles while living in a house on a holiday park in Limburg were broadcast by RTL news.

The photos came from police footage of the four men and were made during a two hour meeting between the suspects and two undercover police officers.

The police were posing as arms traders who could supply weapons for an attack and the holiday house was bugged to collect evidence, RTL said.

The four were arrested that same day.