Powerful syndicates engaged in the illegal business at times use explosives, displacing big chunks of soil for the hidden rocks, making hills vulnerable.

Iandslides have become rampant, particularly in the rainy season, and brooks are changing their courses due to this, sources said.

Already, brooks in many areas have dried up or changed their courses, they said.

The illegal stone collection continues throughout the year but dry season is the best time.

There are at least 30 such illegal quarries only in Kawkhali upazila in Rangamati district from where stones are collected illegally.

This correspondent visited one such quarry in Ghagra village in the upazila.

Local people said they earn Tk 20 to Tk 25 for extraction of one cubic feet of stone. Accumulated stones were seen on yards of almost every household.

It was gathered from villagers that the district administration and the Department of Forest (DoF) are indifferent to the huge extraction of stone. They said they never face any obstruction from the administration in extracting and transporting the rocks.

On investigation, it was gathered that the DoF had once issued 'permits' for stone extraction without any study on its impact on the ecology.

Issuance of permit was stopped in early 1994 but the illegal extraction continues.

Earlier, rocks were collected by some contractors on orders from government departments concerned for their use in building roads and protecting river embankments in the CHT.

As these have good demand and earn hefty profit, some powerful syndicates have been formed with blessings from certain people in the administration and the DoF, the sources said.

As the pebbles available in this region are economically attractive, illegal extractors operate in more than 100 quarries in the entire CHT region now, said Kalam, a sub-contractor in Rajostholi. He supplies rocks to big buyers.

The quarries are in Ghagra, Wagga, Fatikchhari and Kolompoti in Kawkhali; Bondukvanga in Rangamati Sadar; Paindong, Moidung, Doluchhari, Punorbasonpara, Tanchagyapara and Thanchi in Bandarban; and Rangarh, Matiranga, Guimara and Lakhmichhari in Khagrachhari district, according to contractors.

When contacted, Additional Deputy Commissioner (Revenue) Mahfujul Hugue said he has ordered the Kawkhali UNO (Upazila Nirbahee Officer) to visit the areas and give a report. The step was taken after receiving a complaint from a local man, the ADC said.

Talking to this correspondent, Zahir Uddin Ahmad, Divisional Forest Officer (DFO) of CHT South Forest Division, said they will take action against illegal extractors.

"As hill cutting is strictly prohibited, extraction of hard rock is also illegal", he said.He said illegal extraction is threatening the ecological balance in the hills.

He expressed his concern that stone extraction also affects flow of water underneath the soil, which may ultimately turn the hills barren.