Canada's lone Green Party member of parliament, Elizabeth May, on Thursday decried the so-called "ocean fertilization" of the Pacific with what she claimed was Ottawa's tacit approval.

The government however denied any involvement.

May pointed to an article in the British newspaper The Guardian in which California businessman Russ George said he conducted a massive ocean fertilization test last summer, dumping 100 tonnes of iron sulfate off British Columbia's coast in a geoengineering experiment.

The iron has reportedly spawned an artificial plankton bloom as large as 10,000 square kilometers. The aim was twofold: enriching the food chain and increasing sea life for a region that depends on fishing and hoping the plankton will absorb carbon dioxide.

May accused the Canadian government of knowing about the project and letting it happen, but authorities denied any involvement and said they have launched an investigation.

"This kind of experiment is very, very risky business. Scientists have warned us it can destroy oceanic ecosystems, create toxic tides, and aggravate ocean acidification and global warming," May said in a statement. "The long-term absorption of carbon dioxide in water is also contested.

"The fact that federal officials may have known about this and let it happen is disturbing. Have they allowed a Californian rogue investor to play with fire at the expense of Canada's environment?"

The experiment was also harshly criticized at a key UN meeting of 70 environment ministers in Hyderabad, India on halting the depletion of Earth's natural resources.

Adam Sweet, spokesman for Environment Minister Peter Kent, told AFP that company representatives met with Environment Canada officials in May and "were informed that 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.

The company made no request for a dumping permit, he added, and the enforcement branch of Environment Canada launched an investigation on August 30 into an alleged incident.