Six climate protesters who scaled Britain's tallest building have been arrested on suspicion of aggravated trespass, Scotland Yard said tonight.

The group of female activists for the environmental charity Greenpeace reached the top of the 310-metre Shard building in London after 15 hours of climbing.

The group's youngest member - 23-year-old Wiola - broke away from the group to climb the final few metres and unfurl a banner with ''Save the Arctic'' written across it.

Minutes later the six protesters were escorted out of the building by police and driven away in an unmarked van.

Read: Commuters gaze in disbelief at Shard climbers

The stunt began at around 4am this morning with the six activists climbing a ladder out of the roof of a lorry parked near The Shard.

They first scaled the roof of London Bridge Station before transferring onto the tallest building in western Europe.

The ascent began this morning with the protesters climbing out of the roof of a parked lorry Credit: David Sandison/Greenpeace/PA Wire

Greenpeace released this photo showing a training exercise in which the climbers practised leaving the lorry via a roof hatch in order to avoid security guards.

Greenpeace protest climbers in training Credit: Twitter/@GreenpeaceUK

The six experienced climbers ranged in age from 23 to 33 and came from all over the world.

Greenpeace said they had been in training for the stunt for a long time and that every detail had been meticulously planned.

Read: Who are the Shard protest climbers?

The six Greenpeace climbers who made the ascent Credit: David Sandison/Greenpeace/PA Wire

The women said their climb was intended to put Shell and other oil companies into the spotlight. The site was reportedly chosen because it overlooked Shell headquarters in London.

The activists aimed to raise awareness of the efforts being made to exploit fossil fuel resources in the Arctic, and the associated safety and and environmental risks.

An activist unfurls a banner near the top of The Shard Credit: Anthony Devlin/PA Wire

A** Shard spokesman said that in the interests of public and protester safety, the viewing platform of the **Shard had been closed to visitors.

But for the spectators following the feat on the ground and via social media around the world, it was a spectacle worth seeing.

Onlookers watch as a group of six protesters scaling the Shard Credit: Sean Dempsey/PA Wire

One climber, Victoria Henry, 32, a Canadian living in Hackney, London, said this morning: "We'll try to hang a huge art installation 310m up that will make Shell think twice before sending their rigs into the Arctic.

"It's going to be really hard work, it's going to be nerve-shredding for all of us and we may not succeed, but we're going to do everything we can to pull it off.