Canadian environmentalist David Suzuki says he has left his eponymous foundation so he can continue to speak out about issues without damaging the organization's charitable status.

Suzuki, who created the Vancouver-based David Suzuki Foundation in the early 1990s, published an open letter on the organization's website Friday explaining his decision.

"I want to speak freely without fear that my words will be deemed too political, and harm the organization of which I am so proud," he said.

"I am keenly aware that some governments, industries and special interest groups are working hard to silence us. They use threats to the foundation's charitable status in attempts to mute its powerful voice on issues that matter deeply to you and many other Canadians," he added.

Suzuki says opponents have been attacking him personally as a way of marginalizing his environmental organization.

"This bullying demonstrates how important it is to speak out," he said.

While Suzuki decided to leave the board of directors last year, he says he remains one of the foundation's most active volunteers and a major donor.