Protesters have denounced Shell’s "reckless" Arctic campaign, after it was forced to abandon drilling when a test of its protection systems failed.

Greenpeace says the oil company used "stock-car race" recklessness in testing its capping stack to prevent a Gulf of Mexico-style blowout.

As rising temperatures expose more land for exploration, prospectors are rushing to the far north in the hope of carving out a new mineral frontier.