An American company is poised to dump iron filings in the sea off the Galapagos Islands in an experiment designed to remove carbon dioxide from the atmosphere.

Planktos Inc, a “geo-engineering” company, intends to sell carbon “credits” to individuals who want to offset their personal greenhouse gas emissions. But the proposal has alarmed the American government and scientists on both sides of the Atlantic.

Conservationists claim that the dumping of iron filings without a permit is illegal under the international London Dumping Convention and under American law.

The practice of “seeding” infertile areas of the ocean with iron filings is known to create plankton “blooms” which absorb thousands of tons of carbon dioxide, but environmentalists believe the effects on the Pacific ecosystem have not been properly researched.

They allege that the San Francisco company may have carried out experiments with iron filings in 2002 from a yacht loaned to them by the singer Neil Young.

Planktos’s Web site says that it will begin dumping 100 tons of iron filings this month in a 100-square-kilometer area off the Galapagos from its ship, the Weatherbird II, a U.S.-flagged vessel. It says: “Planktos will begin plankton restoration by replenishing forest-sized areas of ocean with natural iron-rich dust, just as Mother Nature does.”

However, according to documents submitted by the American government to the London Dumping Convention, currently meeting in Spain, the company said it would use “a non-United States flagged vessel for releasing the iron so as not to be subject to regulation under the United States Ocean Dumping Act.” It says that the company has not received any authorizing permits from the U.S. authorities, nor has it carried out any environmental impact assessments.

Jim Thomas, of ETC, a Canadian environmental organization, said: “The overwhelming scientific conclusion based upon numerous governmental and intergovernmental experiments is that iron seeding is risky and may only temporarily sequester carbon dioxide.”