An explosion hit a coronavirus testing centre in a town north of Amsterdam shortly before it was to open on Wednesday, breaking windows but causing no injuries, Dutch police said. 

The blast was in the town of Bovenkarspel, police from the province of North Holland said in a statement. They said they had cordoned off the area to investigate. 

According to local media report, the explosion took place shortly before 7:00 am and the test centre appears to have been the target. 

Broadcaster NOS said a metal pipe exploded, but this has not been confirmed. 

The number of positive test results in the Bovenkarspel region has been rising sharply for several days, particularly in nearby Hoorn. Hoorn is now fourth in the list of towns and cities with the most infections per head of the population. 

This is not the first time a test centre has been the target of an attack. Before Christmas, vandals set fire to the test centre on the former island of Urk. Windows were also smashed at test centres in Amsterdam and in Urmond in Limburg in December. - Reuters, Dutchnews