In the latest incident hundreds of trees aged over 20 years along a section of National Highway 14 in Dak Song District in the Central Highlands province were found earlier this month with their barks stripped away and a white chemical with a strong odor on their trunks.

District forest rangers have also found nearly 400 poisoned trees in Truong Xuan Commune. Each tree was found with three or four holes six to eight centimeters deep and with a diameter of seven millimeters. Officials have not revealed which chemicals were found inside yet.

Le Quang Dan, deputy director of the province’ Department of Agriculture and Rural Development, said his department has filed a complaint with the police.

Most of the 3,000 trees destroyed this year were along National Highways 14 and 28 in Dak Song and Dak G'long districts.

In Dak G'long, authorities have discovered 14 forests with over 2,100 trees destroyed this year, and the police are investigating.

Nguyen Duc Chien, chairman of the district's Dak Ha Commune, acknowledged that in his commune locals do destroy pine forests to clear land. It has 15 hectares (37 acres) of pine forests, he said.

"They drill small holes or strip off the barks and then pour in herbicides."

This method makes it very difficult to catch the culprits red-handed, he said.

Nguyen Quan Truong, deputy director of Dak Nong's Forest Protection Department, said authorities have been unable to catch the culprits in most cases.

He said the department is going to reclaim all pine forest areas that had been destroyed and encroached upon for afforestation.

Last May authorities in neighboring Lam Dong Province began an investigation after over 10 hectares of pine forests in Lam Ha District with more than 3,000 trees were destroyed.

They have arrested four people believed to have cleared the land for cultivation and sale.

The Central Highlands has lost nearly 358,800 hectares (14 percent) of forests between 2008 and 2015, according to a report by the Central Highlands Steering Committee.

Most of the trees were chopped down by illegal loggers or cleared to make way for cash crops, roads or hydropower plants.