The protests aim to highlight the lack of customary land rights in Malaysia, where development is forcing indigenous communities off land that they have lived on for generations without owning it legally.

Police detained 15 community representatives outside the Sarawak state government Wednesday while they were trying to hand over a protest note on the building of new hydroelectic dams, said Adrian Lasimbang, president of a local group, Indigenous Peoples Network of Malaysia. The activists were released later.

Lasimbang said the indigenous communities were afraid they would lose their homes without adequate compensation if the government pushes ahead with the construction of 12 new dams.

"Our main concern as indigenous people is that the government keeps disregarding the rights of customary land," Lasimbang said. "It's the government's failure to recognize land rights."

Construction has started on one of the dams in an area known as Murum and is expected to displace some 1,000 people of the Penan tribe, Lasimbang said. The dam, to be completed by 2013, is expected to supply 944 megawatts of electricity.

The other dams are in various planning stages. Lasimbang says those will displace thousands more. Some 10,000 people were already moved for the 2,400-megawatt Bakun dam, which is expected to be completed next year.

Fauzi Shahab, director of Electricity Supply Sarawak, said more dams are needed to supply additional electricity but plans for all of them have not been finalized. He said the state's consumption is increasing from less than 1,000 megawatts currently as more industries are being set up.

"We need those dams to meet our demand," he said. "We need additional power supply."

But Lasimbang and Mark Bujang, a leading activist who was among those detained Wednesday, said communities should have been consulted properly before approving any dams.

Bujang said tribes were expected to step up their protests.

"A lot of people are now becoming aware that their land is going to be affected," he said. "The government's way of consulting them is, 'When are you going to move?'"

He said community leaders erected barricades to block construction workers from the Murum dam area, but police dismantled them. They are expected to re-erect the barricades if the government refuses to cooperate, he said. Government officials could not immediately be reached to comment.

In Sarawak, 24 indigenous tribes, including about 16,000 Penans, live mostly in poor settlements in the jungle.