The world hydroelectric industry's decision to meet in a Malaysian state where dams have uprooted rainforests and native peoples is drawing bitter fire from environmental and tribal groups.

The International Hydropower Association's (IHA) four-day biennial meeting to push "sustainable hydropower" opens Tuesday in Kuching, the languid capital of Sarawak state on Borneo island, and a highly contentious choice.

Sarawak's powerful boss is widely accused of felling huge swathes of rainforest in a much-criticised dam-building drive.

Opponents of Taib Mahmud -- Sarawak's chief minister for 42 years -- plan to hold their own "parallel congress" in Kuching and other protests, bringing to the capital a resistance campaign previously confined to the interior.

"The Taib government is using the IHA name to 'greenwash' all the damage it has done," said Peter Kallang, head of Save Sarawak Rivers, a coalition of local NGOs and tribal groups.

"The IHA also will promote dams and get more business. It's scandalous."

Malaysia's largest state, yet one of its poorest, Sarawak was a vast jungle wilderness of mighty rivers and hunter-gatherer tribes.

But activists say 95 percent of primary forest has been destroyed, accusing Taib of profiting through his grip on land and timber concessions.

Swiss-based forest-protection group Bruno Manser Fund (BMF) estimates his worth at $15 billion, based on financial and corporate records, which would make him Malaysia's richest man.

Taib, 76, is regularly cited by anti-graft groups as the prime example of endemic corruption, which watchdogs say bleeds Malaysia of billions of dollars annually.

Yet Malaysian authorities have failed to act against Taib, whose political party is vital to keeping the 56-year ruling coalition in power.

"He is basically untouchable," said BMF head Lukas Straumann.

Taib's office did not respond to requests for comment. He has previously denied wrongdoing and defended his policies as necessary to develop Sarawak.

Prime Minister Najib Razak's office declined comment.

"IHA is pleased to be convening its congress where hydropower is under focus, and where we can share knowledge and experience," IHA President Richard Taylor said in emailed comments to AFP, adding the congress will hear "alternative" voices.

But Kallang said those voices will be chosen by Taib, and that poor native stakeholders are excluded by high delegate fees.

The IHA board includes the head of Sarawak's Taib-linked energy firm, which Kallang said raises questions about how Kuching was chosen.

Activists say Taib and his family, through control of some of Sarawak's biggest companies, pocket huge kickbacks for ill-advised big projects.

Malaysia's biggest dam, Sarawak's Bakun hydroelectric facility, has been called a "monument to corruption" by Transparency International (TI), displacing more than 10,000 people, many now living in squalid resettlements.

Officials admit Bakun will produce twice as much energy as Sarawak needs, yet plans for up to a dozen more dams have been mooted. Construction has begun at one, sparking native protests last year.

Resource-rich Sarawak remains poor and leaders are keen to diversify from mining, agriculture and forestry into heavier industries, saying ample power is needed to lure foreign investment.

Josie Fernandez, secretary-general of TI's Malaysia office, said there are grave concerns about graft and further ecological damage from the industrial drive, adding Sarawak's people have not benefited from Taib's development.

"Sarawak is so rich in resources. It could have been developed for the good of its people, but hasn't," she said.

Renewable hydropower has received a boost amid climate-change concerns, especially in Asia with its growing energy needs. But projects in the region are often plagued by allegations of corruption and environmental and social harm.

Straumann said the Sarawak congress weakens the IHA's credibility in addressing such problems.