Police have revised the size of the haul of illegal fireworks seized in raids in Rotterdam and Wezep near Zwolle on Wednesday to 2.6 tonnes.

Four people were arrested during the raids and police originally said they had confiscated 1.8 tonnes of fireworks.

The police action was the result of months of investigation following the arrest of two teenagers in Spijkenisse who were carrying illegal fireworks. The trail led to two addresses in Wezep and the Rotterdam district of Hoogvliet.

On Wednesday police found a minibus stuffed with fireworks at both locations and four men, aged 42 to 53 were arrested.

On Wednesday evening, police netted a further 800 kilos of illegal fireworks and a marijuana plantation at a house in Hazerswoude-Rijndijk, east of Leiden.

The police were called after eyewitnesses reported seeing a large number of fireworks being moved into the house from a delivery van. Two men, aged 38 and 29 were arrested.

The same evening, 300 kilos of fireworks were confiscated at a flat in Zoetermeer, which included Chinese firecracker rolls.