Another nine were rescued from the wreckage and admitted to hospital where their condition was listed as stable. There were about 20 passengers on board at the time.

“The bus had stopped at the Kollupitiya stand to pick up more passengers when the tree crashed on it,” a police official told AFP.

“It had rained overnight and the tree had become unstable.”

He said an investigation was launched to determine whether the municipal government had failed to properly maintain trees lining streets in the upmarket neighbourhood.

Sri Lanka sees an average of around seven people killed on its roads each day.

Last year, a total of 2,536 people were killed in road accidents around the island nation.