Six Greenpeace protesters who scaled the Shard in central London have been arrested on suspicion of aggravated trespass.

The activists scaled Europe's tallest building in a protest over plans by oil producer Royal Dutch Shell to carry out drilling in the Arctic Circle.

The group reached the top of the building after 15 hours of climbing.

Once at the summit, two of the campaigners unfurled a 32ft by 32ft blue flag with "Save the Arctic" written in white across it.

John Sauven, executive director of Greenpeace UK, said: "It is an honour to stand here at the foot of Europe's highest building and witness this remarkable achievement by these women.

"If Shell continues to ignore the huge groundswell of support for protecting the Arctic then they will do irreversible damage to their reputation."

The six women started their climb in the early hours of the morning by climbing on the roof of London Bridge station, at the base of the building.

Ambulances waited below while the climbers posted live video of their ascent to Greenpeace's website.

A spokesperson for Shell said: "Recognising the right of individuals to express their point of view, we only ask that they do so with their safety and the safety of others in mind."

Shell cancelled its 2013 Arctic offshore drill season after disruption there last year. But it plans to send ships to study sites around oil prospects in the Chukchi and Beaufort seas, according to permit applications.

The Arctic may still hold 13% of the world's undiscovered oil and 30% of its gas.

"Shell is leading the oil companies' drive into the Arctic, investing billions in its Alaskan and Russian drilling programmes," Greenpeace said in a statement.