Teenage climate activist Greta Thunberg has apologised for saying political leaders who deny a climate emergency is at hand should be put “against the wall” – a comment taken by critics as an endorsement of violence and mass executions.

The 16-year-old Swede made the comment in a speech to young activists in the Italian city of Turin on Friday after departing the deadlocked UN climate summit in Spain.

Thunberg later said her intent was lost in translation, explaining that the term in her native tongue means putting someone on the spot with tough questions.

“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 on Saturday.

Before catching a train back to Sweden, Thunberg told the Turin crowd that world leaders were running away from their responsibility to fight climate change.

Traveling on overcrowded trains through Germany. And I’m finally on my way home! pic.twitter.com/ssfLCPsR8o

— Greta Thunberg (@GretaThunberg) December 14, 2019

“We have to make sure that they cannot do that,” she said.

“We will make sure they, that we put them against the wall, and that they will have to do their job and to protect our futures.”

But some right-wing opponents of efforts to stabilise the world’s weather chose to interpret her comment as a call to round up climate-change sceptics and organise a firing squad.

Thunberg tweeted that she and the youth movement she inspired oppose all forms of violence.

“It goes without saying but I say it anyway,” she wrote.

… improvise speeches in a second language.
But of course I apologise if anyone misunderstood this. I can not enough express the fact that I – as well as the entire school strike movement- are against any possible form of violence. It goes without saying but I say it anyway.

— Greta Thunberg (@GretaThunberg) December 14, 2019

On Thursday, US President Donald Trump hit out at the teen saying she needs to “work on her anger management problem”.

Ms Thunberg quickly responded by changing her Twitter bio to: “A teenager working on her anger management problem. Currently chilling and watching a good old fashioned movie with a friend.”

-with AAP