Greenpeace activists have scaled the heights of Barcelona’s famous Sagradia Familia cathedral to demand the release of 30 colleagues detained in Russia. Several members, suspended on ropes, unfurled pictures of their fellow-campaigners on the 50th day since their arrest.

In a similarly eye-catching move the group has released video of what appears to be Russian naval forces seizing its ship the Arctic Sunrise in international waters.

The vessel, which had been used in a protest against Russia’s first offshore Arctic oil rig, was towed to the port of Murmansk.

Russian investigators initially charged all 30 with piracy but said last month they were changing the charge to hooliganism. Greenpeace says its actions were entirely peaceful.

If convicted the activists face up to seven years in prison. Russia’s detention of the Greenpeace group has been heavily criticised in the West.