Officials in the Dutch town of Voorburg are removing four names from the war memorial in the town park after historians pointed out they belonged to people who sided with the Nazis during World War II.

The memorial contains the names of more than 400 locals who died in World War II, but three of them have since transpired to have been Nazi collaborators, the AD reported on Wednesday.

The makers of the monument, which was unveiled in 2007, had simply looked up the local deaths register for names, without double-checking their backgrounds.

The national war institute NIOD has confirmed that the three sided with the Nazis. Spokesman Hubert Berkhout told the paper mistakes were sometimes made on monuments erected after the war, but rarely nowadays because so much other information is available.

The fourth name to be removed is that of a black marketeer who was killed in a fight with the resistance, the AD said.