Genetically engineering algae as a source of biofuel has potential risks to the environment that demand study, U.S. scientists warn.

Cultivating genetically modified algae for this purpose should be subjected to independent studies to explore any potential unintended consequences, researchers writing in the journal BioScience said.

A critical concern is whether genetically engineered algae would be able to survive if they escaped into the wild, lead author Allison Snow, professor of evolution, ecology and organismal biology at Ohio State University, said.

"If they're grown in big, open ponds, which is mainly what we're talking about, could the newer types of micro-algae get out into nature and mingle?" she asked.

"We need to know if they can survive and whether they can hybridize or evolve to become more prolific when they get out of a controlled environment."

"If they can survive, we also need to know whether some types of genetically engineered blue-green algae, for example, could produce toxins or harmful algal blooms -- or both," Snow said.

Genetic engineering of algae is being considered to create strains that can grow rapidly because mass quantities would be needed to produce adequate biofuel supplies.

Snow has served on national panels that monitor and make recommendations about the release of genetically engineered species into the environment.

"The applications are new and the organisms are less well-known. They range from being very tame 'lab rats' that won't survive in nature to wild organisms that can presumably cross with each other unless some measures are taken to prevent crossing," she said.

"It's a very new situation."