The plan indicates that densely-populated areas like Maghbazar, Tejgaon, a part of Gulshan, Badda and Rampura along the canal will face severe adverse consequences if the canal and its catchment areas are earth-filled.

According to the plan, Begunbari canal is to be preserved as a water body, said Prof. Nazrul Islam, honorary chairman of the Centre for Urban Studies. "Government is well-aware of the encroachments but it is not taking effective measures to save it."

Environmentalists have long been demanding preservation of the canal as a floodwater retention plain, he said.

Rajdhani Unnayan Kartripakkha (Rajuk) itself has contravened the Dhaka Metropolitan Development Plan (DMDP) through development works on the canal, Prof Islam said.

"The Rajuk has drawn a plan, as part of its 13-acre Sonargaon-Hatirjheel development project, to restore the canal as a strong natural sewage discharge system stretching up to Rampura Bridge," said Md Shahid Alam, the immediate past chairman of Rajuk.

"Rajuk could have gone for legal action against encroachments on the Begunbari canal as per wetland conservation law but it has not yet done so," said Alam.

As per recommendations in the DMDP, detailed area plan is required for Begunbari canal "to preserve open space and recreation areas together with its main drainage and transportation functions and proposed water transport terminal."

The low-lying areas along the Begunbari and Hatirjheel canals constitute a major flood retention plain in the heart of the city, according to environmentalists.

As a consequence of filling up the canal, Maghbazar in particular will be the worst affected by waterlogging with slight rainfall.

Influential land grabbers and developers have always been eyeing on this open space as potential source of money making.

Prime Minister's Principal Secretary Kamal Uddin Siddiqui, who heads the good governance committee at the PMO, expressed his resentment at the ongoing earth-filling in the Begunbari and Hatirjheel canals at a meeting on December 10 last.

"The committee in a resolution clearly instructed Bangladesh Railway to take measures to stop earth filling in the Begunbari canal, re-excavate the portion filled up for setting up two CNG stations and evict other illegal occupants," said a member of the committee.

The canal has suffered the latest encroachment by one Badrul Alam and Company which has occupied approximately one acre area at the corner of Panthapath and Tongi Diversion Road with the canal flowing across, by dint of a lower court order in the name of his company Chowdhury Group in December last.

Chairman of the company, Badrul Alam Chowdhury said, "We have purchased the land from the son of one Sobhan Bepari, who has legal documents from the settlement office." But railway officials said the land acquired in 1953 belongs to railway.

In December 2005, railway served an eviction notice but the land claimant filed a writ petition at the High Court which issued an order to maintain status quo on the matter.

Railway's Divisional Estate Officer Kabir Siddiqui said, "I have instructed our legal officer to contest the High Court stay order."

"We are trying to file an affidavit to vacate the stay order obtained by the encroacher," said Litigation Inspector of Bangladesh Railway Md Salahuddin. "Claim on the land by Badrul Alam and Company is false," he said.

Various parties including Railway and PDB claim ownership of land in the canal, said Chowdhury, adding that even government agencies are divided over its ownership.

"Sobhan Bepari is not the owner of the land at all as he lost three times in legal battle with the railway," said Salahuddin.

Syeda Rizwana Hasan of Bangladesh Environmental Lawyers' Association said the land grabbers take advantage of the government's reluctance to take action against those who grab lands and water bodies with forged documents.

She said the grabbers manage to tamper with the land records before they embark on a public land and produce forged documents when challenged. Grabbers easily gobble up open spaces and wetlands in absence of demarcation, she added.

"Even if there is any demarcation, Rajuk does not make it public," she said.