The oil slick on the Shela and Pashur rivers after a tanker loaded with furnace oil sank near the Sundarbans early Tuesday. Photo: Star/Banglar Chokh

A thick layer of oil was floating on the waters of the Shela and Pashur rivers and smearing soil and plants on the shorelines and adjacent canals, as the oil spillage could not be stopped till yesterday evening.

As of last evening, the slick spread over a stretch of more than 50km -- up to Koromjal in the upstream and up to Kachikhali in the downstream, forest officials said.

Salvage operations could not be started either, as no rescue vessels reached the accident spot in Mongla.

Shipping Minister Shajahan Khan told the BBC last night that one rescue boat -- Nirbhik -- was on its way and would reach the site “very soon”. Another salvage vessel named Kandari-10 is heading towards the spot and is expected to be there today.

Officials hope the rescue operations would begin today.

The spillage started on Tuesday morning, after an oil tanker carrying 3.58 lakh litres of furnace oil and eight crew members sank near Mongla around 5:00am.

The tanker, Southern Star-7, went down after a cargo vessel hit it from behind. Of the crew, Master Mokhlesur Rahman remains missing while the seven others managed to swim ashore.

Coast Guard Commanding Officer Mehedi Masud told The Daily Star yesterday that the leaking seemed to have slowed, meaning almost all the oil had already gushed out.

The spill has spread over about 50km harming the largest mangrove forest in the world. Photo: Star/Banglar Chokh

The shipping ministry yesterday banned playing of any vessels through the Shela river route until further notice, reports UNB.

The oil slick will have a severe impact on the aquatic lives and the mangrove plants grown along the shorelines where the thick layer of oil has gathered. Fish and other aquatic lives would start dying in a day or two while the mangroves might start dying after a month. The spill will also cause a huge problem on the shorelines of canals and rivers the animals of the mangrove forest drink from, wildlife experts said.

“Not only the aquatic resources, all the animals of the Sundarbans will be affected by this accident as all the animals come to the rivers and canals to drink water,” Monirul H Khan, an eminent tiger expert, told this paper.

But the most horrific thing is that the oil would be in the ecosystem for up to 50 years, he added.

Rubaiyat Mansoor, the Bangladesh coordinator of Wildlife Society, who is at the accident site, said: “I have already heard from some fishermen that fish started dying at different points.”

Amir Hossain Chowdhury, divisional forest officer, east zone of the Sundarbans, said they were trying to remove the oil manually by using fishing nets.

Forest officials are also trying to put some fishing nets on the mouth of the canals so that oil cannot enter into those. At least 20 canals connected with the Shela river have already been polluted, he said.

The shipping ministry formed a three-member committee to investigate the accident.

The Sundarbans Forest Division formed a separate committee and asked the committee to submit a report within three days.

Meanwhile, the forest department filed a general diary against the owners of the oil tanker and the cargo vessel, saying that the two ships damaged Tk 100 crore wealth of the forestry.

M Giasuddin, managing director of Harun & Company, owner of the tanker, filed a case against the cargo vessel owner with Mongla Police Station.