Two men from Belgium are suspected of setting a large fire in the cave system on the border between Maastricht and the Belgian village of Kanne last week. The fire started on Thursday night and is still burning, RTL Nieuws reports.

On Saturday morning the fire department gave up on extinguishing the fire and are now just keeping it under control while it burns out. That can take weeks. Both Maastricht and Kanne are covered in smoke. "People must take a week or two of smoke and stench into account", a spokesperson for the fire department said to the broadcaster.

The fire is believed to have started in a cave where a Kanne farmer stored his hay. He quarreled with the two suspected Belgians and called in the police, according to RTL. The Belgian authorities questioned the men on Friday morning, but had to release them due to lack of evidence. As the arson happened on Dutch territory, the investigation was transferred to the Dutch police. The two Belgian men are still considered suspects.

The fire department had to stop actively fighting the fire for safety reasons. Temperatures in the cave system are too high and there is a risk of collapse. "We can't send any people in there", the fire department spokesperson said. 

Twee Belgen verdacht van aansteken grottenbrand in Riemst https://t.co/AJ7n5ks1mE #nieuwsblad pic.twitter.com/VfGQuwe8Yi

— Het Nieuwsblad (@Nieuwsblad_be) July 24, 2017

Belgen verdacht van aansteken grottenbrand Maastricht https://t.co/vShOElJfx6 pic.twitter.com/wf8y5Fyegq

— RTL Nieuws (@RTLnieuws) July 24, 2017