Feyenoord’s general manager Robert Eenhoorn said he “cannot be happy” with their 5-2 victory in Leeuwarden, adding “frustration prevails too much for that”.

“This problem obviously does not only affect Feyenoord and is unfortunately something we have been unable to put a stop to for decades,” Eenhoorn said.

“We will therefore have to sit down again with all stakeholders, clubs, the KNVB [Dutch football association], and the authorities to look for a solution together.”

Leeuwarden mayor Foort van Oosten also condemned the incident and promised an investigation, while the Dutch football association said it would revisit its protocols for incidents of disorder.

The game resumed despite the injuries to the fans, but it would have been abandoned had a player or match official been hit.

“That doesn’t feel right,” Jan Bluyssen, the KNVB’s manager of professional football competition affairs, told Dutch news agency ANP.

“We need to examine whether the protocol is still appropriate and how we might want to adjust it.”