Resort towns on the Belgian coast announced measures Sunday to stop day-trippers after beach fights broke out between police and youths told to leave for refusing to respect coronavirus safety measures.

Knokke-Heist and Blankenberge, two popular towns on the Flemish northern coast near the border with the Netherlands, said they took the step so as to "guarantee public security."

Police arrested several people Saturday on Blankenberge beach after a brawl broke out between officers and youths they had told to leave for refusing to respect virus safety measures. 

The two towns and the coast generally have been swamped with visitors seeking relief from a heatwave as the country also grapples with one of the most serious coronavirus outbreaks in Europe.

The ringleaders were barred from the resort which was also closed to day-trippers, Blankenberge mayor Daphne Dumery said. 

"We need a quiet period... Anyone who comes to Blankenberge must have a good reason to be here. With this step, we are trying to restore calm," she added.

The nearby upmarket resort of Knokke-Heist took a similar step after "dozens of incidents, during the day and the night," a city council statement said.

The council "felt obliged to take drastic measures. To ensure public security, day visitors will no longer be allowed."

There will be road checks where people will have to show proof that they either live in the town, are staying in a hotel or rented apartment, or work there, the statement said.

"All vehicles will be checked. Anyone who does not have a valid reason to be in Knokke will have to turn around and leave immediately."

The SNCB train operator told passengers to check whether they would be allowed to visit the two towns before setting out.