Climate activist Greta Thunberg and Germany’s national railway company went head-to-head on social media Sunday after the teenager posted a photo of herself sitting on the floor of a train surrounded by baggage and with an empty fast food container at her feet.

She posted the tweet late Saturday with the comment: “Traveling on overcrowded trains through Germany. And I’m finally on my way home!”

Supporters pitied the “exhausted” 16-year-old Swedish activist for not being able to be seated on the train for the ride home from Madrid, where she was attending the U.N. COP25 climate conference.

They wished her a safe trip home after months of touring climate events in Europe and the United States.

Traveling on overcrowded trains through Germany. And I’m finally on my way home! pic.twitter.com/ssfLCPsR8o — Greta Thunberg (@GretaThunberg) December 14, 2019

But German railway company Deutsche Bahn struck back. It suggested Thunberg may not have spent the whole time sitting on the floor as she alleged and instead chose to neglect her booked first class seating for the sake of a photo opportunity.

The railway company wrote in a statement to the media Thunberg had a seat in first class between Kassel and Hamburg and other members of her team were already sitting there and enjoying its lush comforts from Frankfurt onwards.

Later on Sunday, Deutsche Bahn tweeted twice more in regard to Thunberg’s train travels through Germany.

In the first tweet, the company thanks the teenager for supporting Deutsche Bahn’s battle against climate change and pointed out the train she used had been running 100 percent on eco-friendly electricity.

In the second tweet, however, Deutsche Bahn suggested Thunberg hadn’t spent the entire train ride sitting on the floor.

The company pointed out to the teenager, “it would have been even nicer if you had also reported how friendly and competently our team served you at your seat in first class.”

The 16-year-old Swedish activist later sought to draw a line under the matter by acknowledging she eventually got a seat and that overcrowded trains are actually quite a good thing after all because it means less cars on the road.

Thunberg’s backdown was the second time in less than 24-hours she had apologized for an intemperate use of speech.

Earlier in the day she apologized for saying politicians should be put “against the wall” after critics took it to mean that she was advocating violence.

The 16-year-old Swede made the comment in a speech to young activists in the Italian city of Turin on Friday. She blamed the subsequent backlash on her meaning being lost in translation.

“That’s what happens when you improvise speeches in a second language. But of course I apologise if anyone misunderstood this,” Thunberg wrote on Twitter.

AP contributed to this story