A helicopter with four people on board crashed early toay in Sarawak in the third incident in two months, with the fate of the passengers still unknown, a report said.

The privately chartered Bell helicopter crashed 70 kilometres from the state capital Kuching, just five minutes after take-off from the local airport, a spokesman for the Department of Civil Aviation told the Bernama news agency.

"We still do not know the fate of the passengers and the pilot," he said.

Bernama said the personal bodyguard of Natural Resources and Environment Minister Adenan Satem and the private secretary of Sarawak deputy chief minister Alfred Jabu were believed to be among the four on board.

They were accompanying the ministers, who were in another helicopter, to a government function in another district when the incident occured, it added.

Third chopper crash

This is the third chopper crash in two months in Malaysia's largest state.

On July 12, another Bell chopper owned, like the one in Friday's crash, by Hornbill Skyways crashed in the Sarawak highlands, killing all seven people on board.

It took rescuers 17 days to find the helicopter in the dense jungles of Borneo island, which Malaysia shares with Indonesia and tiny oil-rich Brunei.

Last month, three people were killed but seven others survived when a Malaysian air force helicopter crashed while ferrying army personnel and supplies to a border outpost.