SHIPS will be banned from discharging a chemical blamed for killing thousands of seabirds off the Dorset coast, it has been announced.

From 2014 it will be illegal to discharge polyisobutylene (PIB) into the sea during tank cleaning operations.

The decision by the International Maritime Organisation's (IMO) working group on the Evaluation of Safety and Pollution Hazards of Chemicals has been welcomed by wildlife charities.

Martin Cade, of the Portland Bird Observatory, was one of the first to see the devastating impact of the chemical when dead birds were discovered on the Dorset coast in February.

He said: “I’m overjoyed to hear it’s going to be banned. It’s amazing that they were allowed to pump the thing out in the first place and I don’t think the consequences were at all appreciated until these events.”

Alec Taylor, Marine Policy Officer for the RSPB said: "We are delighted with the action taken by the IMO. The global trade in PIB products is increasing and with it the risks to our precious marine environment. Today’s global ban on the deliberate discharge of high viscosity PIBs into our seas is a real step forward and one that we hope will end this particular pollution threat to seabirds and other marine life."

The classification of PIB will be changed and ships will be required to prewash their tanks and dispose of all residues at port. Any discharge of the chemical into the sea will be illegal.

The recommendation was made by the Maritime and Coastguard Agency (MCA) on behalf of the UK Government, following vigorous campaigning by wildlife charities and the public.

Thousands of birds, mainly guillemots, were washed up in two separate incidents earlier this year on the Dorset coast and across the south west.

The majority of the birds were dead but survivors were taken to the RSPCA West Hatch centre where they were cleaned and later released back into the wild.

RSPCA senior wildlife scientist Adam Grogan said: "We welcome this decision. Our staff worked around the clock washing and treating these poor birds in January and April and it was heartbreaking seeing the pitiful state they were in. 

"Hopefully this will help stop incidents like these happening again, and save wildlife from suffering and dying like this in the future.”

Joan Edwards, Head of Living Seas for The Wildlife Trusts, said:  "We welcome today's ban. The thousands of dead and dying seabirds witnessed earlier this year were the most visible victims of mismanagement.

"Impacts on other parts of marine life support systems may have been just as widespread, and more serious. Not to mention the impacts on tourism of dead seabirds on the beach - particularly pressing in south west counties which rely so heavily on summer visitors."