He said the participants at the special meeting — the first of its kind — would “insist” Shell dismantle the rigs.

The OSPAR convention groups Belgium, Denmark, the European Union, Finland, France, Germany, Iceland, Ireland, the Netherlands, Norway, Portugal, Spain, Sweden and Britain along with Luxembourg and Switzerland.

Greenpeace campaigners on Monday boarded Shell’s Brent Alpha and Bravo platforms, which lie northeast of Scotland’s Shetland Islands and are no longer operational, to protest what Greenpeace said were threats to the environment.

The group claimed that Shell’s decommissioning plans would leave portions of four Brent oil platforms at sea with some 640,000 cubic metres of oily water and 40,000 cubic metres of oily sediment, containing an estimated 11,000 tonnes of oil.

Shell responded in a statement received by AFP that it has spent 10 years conducting in-depth research into decommissioning the Brent platforms — and added that its recommendations were the result of more than 300 scientific and technical studies.