Grünheide - Another day, another problem with Tesla's construction site on the southeastern outskirts of Berlin in Brandenburg.

Environmental officials from Brandenburg, the leafy state that wholly surrounds Germany's capital, are investigating Tesla for building a holding tank for a toxic coolant without a permit, Tagesspiegel reported Wednesday.

The officials confirmed to the paper they had inspected the site. "The results of the inspection are not yet in," Brandenburg's environmental protection department reportedly said.

15 temporary building permits

Tesla's Gigafactory has been a thorn in the side of Brandenburg environmentalists since the start and it continues to operate on a raft of temporary building permits - the current problem arises from the 15th preliminary permit. Environmentalists have decried the plant's massive water needs and are also concerned about the effects of its paint shop. 

The current accusation is that Tesla already has a tank for the coolant tetrafluourpropene without the proper permission. German environmental associations NABU and Grüne Liga alerted the authorities after pictures taken by a drone flying over the factory were published on Instagram.

The associations' attorney, Thorsten Deppner, wrote to the Brandenburg environment watchdog, the Landesumweltamt, on 2 July and Tagesspiegel claims to have a copy of the letter. The fear is that acid could leak from the plant in case of a fire - a claim environmentalists have made since last year and which Tesla hasn't been able to counter. 

Tagesspiegel didn't include comment from Tesla in the article.