An Australian couple will sail teenage climate activist Greta Thunberg almost 6,300km from the US to Spain so she can attend a UN climate meeting.

The Swedish campaigner, 16, revealed on Wednesday she had received an invite from couple Riley Whitelum and Elayna Carausu to take her to the COP25 conference in Madrid.

The group - who will sail on a 48ft catamaran called La Vagabonde - will leave Hampton, Virginia this week.

Australian couple Riley Whitelum and Elayna Carausu (far left and far right) will sail teenage climate activist Greta Thunberg almost 6,300km from the US to Spain so she can attend a UN climate meeting

The group - who will sail on a 48ft catamaran called La Vagabonde - will leave the state of Virginia on Thursday (pictured L-R Elayna Carausu, Ms Thunberg, Nikki Henderson from England and Riley Whitelum)

Ms Thunberg had issued a plea on social media for help getting back across the Atlantic Ocean after the summit was moved at the last minute from Santiago in Chile to Madrid due to the protests in the South American country.

'So happy to say that I'll hopefully make it to COP25 in Madrid,' she said in a post on Wednesday.

'I've been offered a ride from Virginia, USA, on the french 48ft sailing catamaran La Vagabonde.

The La Vagabonde yacht which will return Swedish climate activist Greta Thunberg to Europe

Thunberg had issued a plea on social media for help getting back across the Atlantic Ocean after the summit was moved at the last minute from Santiago in Chile to Madrid

The Australian couple have spent several years sailing around the world and have recently had a son, Lenny, together (pictured together with their son)

Ms Thunberg (pictured aboard La Vagabonde) had issued a plea on social media for help getting back across the Atlantic Ocean after the summit was moved at the last minute from Santiago in Chile

Ms Thunberg was interviewed aboard La Vagabonde before departing Hampton, Virginia

'The two Australians Riley Whitelum, Elayna Carausu and Nikki Henderson from England will take me across the Atlantic Ocean.'

Weather dependent, their journey is expected to take about three weeks.

Mr Whitelum said in a statement they had seen 'the beauty of this planet first hand and think that it is something we should all strive to protect.'

'It is something I have considered even more since having a child,' he said.

The Australian couple have spent several years sailing around the world and have recently had a son, Lenny, together.

Ms Thunberg refuses to fly in planes because of the carbon footprint and used a zero-emissions sailboat so she could make it to New York climate summits (pictured addressing the UN General Assembly in New York in September)

They have a YouTube channel boasting more than 1.1million subscribers called Sailing La Vagabonde, which documents their travels onboard the boat.

'Through our videos we hope to inspire others to explore alternative options of living and to spread ocean awareness,' the couple said in their channel description.

Ms Thunberg refuses to fly in planes because of the carbon footprint.

She used a zero-emissions sailboat so she could make it to New York climate summits in September.