A state-linked Malaysian energy firm said Monday it had begun filling the reservoir behind a controversial dam as a group of angry tribespeople protested.

Some 100 Penan tribespeople from seven villages set up a blockade last week on the only road to the remote, $1.3 billion Murum dam on Borneo island in the state of Sarawak, activists said.

"More than 100 Penans have set up a human blockade to demand 500,000 ringgit($156,225) for the loss of their land, property and livelihood," said Mark Bujang, secretary of the Save Sarawak Rivers Network.

The Murum dam is one of a series of hydroelectric facilities planned by the Sarawak state government as it pushes economic development in one of Malaysia's poorest states.

But the building spree has been dogged by controversy.

Activists allege massive corruption while natives complain it has flooded rainforests and uprooted tens of thousands of people.

Sarawak Energy said on its website that the 944-megawatt dam project began filling on Saturday and would be completed within 14 months.

It added that relocation of affected natives was set to be completed by year-end.

"It is disturbing that there are certain groups of people trying to give the wrong impression that when impoundment (filling) starts it will submerge the people who are yet to be relocated," Polycarp Wong, a vice president with Sarawak Energy, said in the statement.

The government of resource-rich Sarawak says it hopes a plentiful supply of hydropower from the state's powerful jungle rivers will attract new industries.

The dam is expected to flood 245 square kilometres (95 square miles) and cause 1,500 Penan and 80 Kenyah natives to lose their homes.

Sarawak natives have staged increasingly frequent protests and road blockades in recent years over the dams.

Sarawak's longtime chief minister Taib Mahmud has faced mounting accusations of enriching himself and cronies through a stranglehold on the state's economy, charges which he denies.

Sarawak is home to the already operating Bakun dam, which Transparency International has condemned as a graft-plagued ecological catastrophe.