Secret police methods to track down people buying illegal fireworks online have resulted in 350 people being sent video warnings by email, RTL news said on Wednesday.

A number of potential buyers have also been warned by letter, a special police task force said. Most of the orders were made to webshops in Poland.

Police have not said how they are tracking down people placing orders for illegal fireworks. The campaign was first announced in early November.

The video warns the buyer they are attempting to buy illegal fireworks and that this is extremely dangerous to themselves and other people. The video also warns the buyer will have a criminal record and may run into trouble with their mortgage provider for storing dangerous fireworks at home.

Every year in the run up to the New Year celebrations, the police make dozens of arrests and seize thousands of kilos of illegal fireworks under the vuurwerkwet (fireworks law). This states that fireworks may only be sold to the public from licensed locations during a few days prior to December 31.

The warnings have also been uploaded to YouTube.