Dutch police have arrested two more people for dumping waste on the A7 motorway during the radical farmers’ protests.

The new suspects, aged 19 and 20 and from Friesland and Groningen, bring the total number of arrests in the investigation to four.

Police have been trying to trace who was responsible for dumping pallets, farm waste, asbestos and other rubbish at different locations on the motorway on July 28 and August 1. The A7 is the main connection between the north of Amsterdam and Groningen, and continues up to the German border.

One driver had a lucky escape when his car ploughed into the waste and was badly damaged, but so far no-one has been injured in an accident caused by protests. Specialists were brought in to clear up the asbestos.

Police also said on Tuesday that the 32-year-old man who was arrested earlier has been remanded in custody for a further two weeks and that more arrests cannot be ruled out.