Eyewitnesses have said the bus was racing with another and the driver had lost control.

But the bus association has ruled out rash driving, preferring to pass the buck onto the state irrigation department.

Accusing the department of callousness, Sadhan Das of the Joint Council of Bus Syndicates said: “The irrigation department had been carrying out dredging in Keshtopur canal and the soil has been dumped on the road. With heavy rains lashing the city and suburbs, the muddy water has made the roads slippery. When the driver slammed the brakes to avoid hitting another vehicle, the bus skidded and fell in the canal.”

State irrigation minister Subhash Naskar denied the allegation. “Nothing of that sort had happened. I have verified that no dredging was underway at that spot,” said Naskar.