A German railway operator has hit back at climate activist Greta Thunberg after she tweeted a photo of herself sitting on a train floor during her trip home from the COP25 climate summit in Madrid.
On Sunday, the 16-year-old tweeted a photo of herself looking pensively outside the train window as she sat on the carriage floor surrounded by her luggage.
"Traveling on overcrowded trains through Germany. And I'm finally on my way home!" Ms Thunberg, who is Swedish, said.
The railway operator, Deutsche Bahn, responded testily, pointing out that the activist had travelled in first-class during her journey through Germany.
"Dear Greta, thanks for supporting us railway workers in our fight against climate change. We are happy that you travelled with us on the ICE 174 on Saturday," tweeted Deutsche Bahn's official account in German.
"It would have been nicer if you had also mentioned the friendly and competent manner in which you were treated by staff at your seat in first class," they added.
The railway then followed up the tweets with a press release, in which they added that Ms Thunberg's travel companions "were sitting in first class from Frankfurt onwards".
Ms Thunberg responded on Twitter, claiming she had found a seat at a stop after Frankfurt, which she said was "no problem".
'No problem'
"Our train from Basel was taken out of traffic. So we sat on the floor of two different trains. After Goettingen I got a seat," wrote the 16-year-old.
"This is no problem of course and I never said it was. Overcrowded trains is a great sign because it means the demand for train travel is high!"
Ms Thunberg's journey through Germany was the last leg of a continent-spanning trip which began when she travelled to New York on a low-emissions yacht last August.
The activist started a worldwide movement last year when she began to strike from school every Friday to protest government inaction on climate change.
Refusing to fly, she has twice crossed the Atlantic by boat in recent months in order to speak at a UN climate summit in New York and the hastily rearranged COP25 summit in Madrid.
Her online run-in with Deutsche Bahn comes just days after a high-profile Twitter clash with US President Donald Trump.
After Ms Thunberg was named TIME magazine's person of the year, Mr Trump tweeted that she had "anger management problems" and told her to "chill".
Ms Thunberg responded by changing her Twitter bio to include the words "currently chilling".
