The world's most diverse marine region is under serious threat and needs urgent protection, environment watchdogs said today.

The Coral Triangle - a 2.1 million-square-mile stretch of ocean straddling six countries - contains 75% of the world's coral species, a third of the Earth's coral reefs, and more than 3,000 species of fish.

Over-exploitation, environmental degradation, a population boom, and climate change are all threatening the area, environmentalists said, and businesses need to map out a strategy to save the Coral Triangle, which provides livelihoods for more than 120 million people.

Philippine President Gloria Macapagal Arroyo said companies could profit while protecting the area.

"As saving the world from fossil fuels can be profitable, so also can saving the Coral Triangle be profitable," she told a two-day conference of Asia-Pacific business leaders.

Lida Pet Soede, head of the Coral Triangle Programme, said the conference aims to involve the private sector in reducing their negative footprint on the environment.

"It is really about companies changing the way they do business in order for them, of course, to have a sustained profitability but also to sustain the livelihood of more than 100 million people," she said.

"If the private sector becomes part of the sustainability, that impact is potentially much larger than the amount of funding that can be mobilised for more conventional conservation."

About 100 people protested outside the conference saying it would only benefit big business at the expense of poor fishing communities. Demonstrators from the Peasants Movement, a fishermen's federation, carried a boat and placards that read, "Our seas and corals are not for sale."

Six Asia-Pacific nations straddle the Coral Triangle - Indonesia, Malaysia, Papua New Guinea, the Philippines, Solomon Islands and East Timor.