She's the 16-year-old schoolgirl who inspired a series of classroom walkouts when her message for faster action on climate change spread from Sweden across the continent.

But while Greta Thunberg spoke to an animated crowd of Existence Rebellion demonstrators at Marble Arch, London, yesterday, reports emerged claiming the teenager's rise to fame was more orchestrated than first thought.

Six months ago an unknown 15-year-old Miss Thunberg camped outside Sweden's parliament next to a hand-written sign that read 'Skolstrejk för Klimatet' (School strike for the climate).

Activist Greta Thunberg addresses hundreds of Extinction Rebellion during a rally at Marble Arch on day seven of protest action

Reports claim the Swedish teenager's rise to fame is more orchestrated than first thought, with both PR consultant Ingmar Rentzhog (left) and her mother well known opera singer Malena Ernman (right) helping her find fame

Miss Thunberg skipped school every Friday to sit on the steps of the Riksdag and soon became a global success following her first TED talk - which now has more than a million views.

But doubts have been raised as to whether the teenager's newfound shift into the spotlight is really the creation of a carefully laid out public relations campaign.

PR consultant Ingmar Rentzhog's We Don’t Have Time climate change PR agency used Miss Thunberg's image to gain funds for his firm, according to Climate Change Dispatch.

But the publication said the teenager's family deny being aware that she would be used in this way, and have since cut ties with Mr Rentzhog’s organisation.

Miss Thunberg said: 'I was briefly a youth adviser for the board of the non profit foundation We Don’t Have Time.

'It turns out they used my name as part of another branch of their organisation that is a start up business. They have admitted clearly that they did so without the knowledge of me or my family.

Greta Thunberg and her mother opera singer Malena Ernman, in her home in Stockholm

Greta Thunberg was born on 3 January 2003. Her father is actor Svante Thunberg, - here with her sister Beata. She is pictured with her other family members

'I no longer have any connection to We Don’t Have Time. Nor has anyone in my family. They have deeply apologised and I have accepted their apology.'

Mr Rentzhog told Vice: 'They think that I am the PR genius behind Greta. That I write her speeches and arrange meetings for her with journalists. That's simply not true.'

It was also revealed earlier this year that Miss Thunberg’s school strike coincided with the launch of a book about climate change written by her mother, well known opera singer Malena Ernman, according to Swiss magazine Die Weltwoche.

The publication said that on the day of the book's release, Mr Rentzhog published a picture of Miss Thunberg in action to his firm's Instagram, having taken a photographer along to the school strike.

He also posted an article about her on Facebook, starting the first of the teenager's publicity.

Yet Miss Thunberg denied that the book launch had anything to do with her personal school strike.

Greta Thunberg (pictured centre) spoke to an animated crowd of Existence Rebellion demonstrators at Marble Arch, London, yesterday

Writing on Facebook, she said: 'My family has written a book together about our family and how me and my sister Beata have influenced my parents way of thinking and seeing the world, especially when it comes to the climate. And about our diagnoses.

'That book was due to be released in May. But since there was a major disagreement with the book company, we ended up changing to a new publisher and so the book was released in August instead.

'Before the book was released my parents made it clear that their possible profits from the book ”Scener ur hjärtat” will be going to eight different charities working with environment, children with diagnoses and animal rights.'

Swedish journalist Henrik Alexandersson also claimed that Miss Thunberg's much-reported on speech to the United Nations Climate Change Conference in Poland in December 2018 was delivered to an empty room.

However clips and photographs from her speech - which went viral - fail to prove or disprove the claim as they centre mainly on the teenager.