At least 19 people have been killed after a fire broke out at an illegal six-storey plastics market in the Indian city of Kolkata.

The fire, which started before 4am local time, was likely caused by a short circuit, said West Bengal fire minister Javed Khan.

It was under control by mid-morning, he said, but toxic gases being released by the blaze were hampering rescue efforts.

A police official, speaking on condition of anonymity, said they were looking for the owner of the building, which was filled with dozens of small shops selling various plastic products.

At least ten people were hospitalised in critical condition and the death toll was expected to rise, Mr Khan said.

He called the scene of the fire "an illegal, unauthorised market".

However, local residents said the market had been operating in the building for nearly 40 years.

They said there was only one entrance to the building, which made rescue efforts difficult.