They said a committee should be formed to investigate such cases and punish all the land grabbers and government officials, who were involved in destroying the forests and hills illegally.

The observations came at a seminar on 'Role of Mangrove Forest in Natural Disasters: Potentials and Threats' organised by Coastal Association for Social Transformation (Coast) Trust at the National Press Club in the city.

The seminar was organised to mark the devastating cyclone on April 29 in 1991 in the southern part of the country that killed around 1.40 lakh people and destroyed resources of thousands of crores of taka.

Speakers said the mangrove forest, which could be a major protection for the 19 coastal districts from major natural disasters, is under tremendous threat for extensive shrimp cultivation, its excessive use in agricultural activities, salinity and industrialisation.

Coast Coordinator Mahmud Selim in his keynote presentation said mangrove forest functions as a safety net for the coastal zones by weakening the speed of typhoon or tsunami, but unfortunately such ecosystem is being destroyed in the coastal zones leaving more than three crore people under serious threat.

Around 4.5 lakh Sundari trees in the Sundarbans have become sick, while petroleum materials discharged by engine boats and ships are threatening its eco-system. On the other hand, cutting trees illegally and cultivating in the forestland and shrimp cultivation are speeding up the deforestation, he said.

Mahmud Selim said land grabbers have totally destroyed the mangrove forest at Galdia Island of Cox's Bazar for shrimp cultivation, and over 6000 hectare of mangrove forest at Chokoria have already been destroyed.

"The whole Sundarbans might go under water due to sea level rise, as the scientists said it will increase by 4 to 26 inches in the next 100 years," he noted.

The keynote presentation, therefore, suggested a green safety net by preserving and developing the mangrove forest in the coastal zone and more forestation in the areas by including it under the budget.

According to Bangladesh Coastal Zone Policy 2005, the government should undertake a forestation programme, but there is no such programme under the forest department.

Mahmud Selim said the people of the coastal zone should be involved in creating awareness on maintaining the mangrove forest, impose ban on any new shrimp cultivation project in such land, and give budgetary allocation for creating mangrove forest.

Chittagong University Prof Tofael Ahmed said an integrated plan of action should be taken in the coastal zone to prevent the production of salt and shrimp cultivation and to preserve mangrove forest.

Former minister AKM Jahangir Hossain said the Sundarbans might be destroyed in the next 20 years due to lack of sweet water.

Jatiya Samajtantrik Dal leader ASM Abdur Rab attended the seminar as chief guest while Aminur Rasul Babul of Coast and former lawmaker Begum Tasmin Rana also spoke on the occasion.