Organizers of a controversial ocean fertilization project off Canada's west coast said Friday officials knew of the undertaking but did not stop it, and that it violated no laws.

The project, carried out by a small aboriginal village together with US businessman Russ George, involved used a fishing boat to scatter 120 tonnes of iron sulphate last August into the Pacific Ocean west of Haida Gwaii, an archipelago off British Columbia.

The move was criticized by environmentalists, aboriginal groups and scientists for violating an international ban on ocean fertilization. It was even cited at this week's meeting of the United Nations Convention on Biological Diversity in Hyderabad, India.

The government has denied any involvement and on Thursday a spokesman for Environment Minister Peter Kent said an investigation into the matter had been launched on August 30.

Adam Sweet told AFP federal officials met project organizers last May and told them "any iron ore deposit in waters, whether inside or outside the Canadian (200 nautical miles) limit, constitutes a violation of the Canadian Environmental Protection Act," unless it is for the purpose of legitimate research.

One of the organizers, John Disney of the Village of Old Massett, insisted organizers followed international legal and scientific protocols, and that at least seven Canadian federal agencies knew of their plan.

"The government knew exactly what we were doing," Disney told a news conference at the Vancouver Aquarium. "The work was performed in international waters, and is lawful."

Organizers said the project aims to test two goals:

One is whether iron dust can boost the ocean ecosystem and increase the struggling population of salmon, a mainstay of the area's culture and economy.

The other is whether iron dust will increase plankton, a species at the base of the ocean food chain, and lead to future profit through the sale of carbon credits.

A project document said satellite images show an increase since August of the affected area's biological activity.

However, Greenpeace spokesman Eduardo Sousa told AFP the project is "rogue science" for commercial purposes.

Evgeny Pakhomov, an oceanographer at the University of British Columbia, said iron seeding is an old idea and was previously tried on a small scale.

But he told AFP most scientists reject it because unintended consequences -- including increased ocean acidification -- are not yet understood.

Disney said Old Massett and not George, whom he called the "chief scientist," initiated the project. George was previously involved in ocean fertilization attempts banned in other countries.

Disney said other scientists were involved, but cited their privacy in refusing to name them.

The Canadian $2.5 million (US$2.52 million) project cost amounts to more than 25 percent of the village's annual operating budget, he added.