Dogs in the Indian city of Mumbai are turning blue, with the cause thought to be dyes being discharged by industry into a river.

Concerns were raised by Arati Chauhan​, head of the Navi Mumbai Animal Protection Cell, who posted pictures online of one dog whose fur had been dyed blue.

"It was shocking to see how the dog's white fur had turned completely blue," she said. It was thought there were about five dogs in the area, a township of Mumbai, with dyed fur.

ARATI CHAUHAN/FACEBOOK Industrial dyes discharged into an Indian river are thought to be responsible for turning dogs blue.

It was thought stray dogs were turning blue after wading into the Kasadi​ River, near the Taloja​ industrial area, to get food, Hindustan Times reported.

READ MORE:

* 22 of the world's most polluted cities are in India

* India builds first 'smart' city as urban population swells

* India plans to sell holy water from Ganges River

The area had nearly 1000 pharmaceutical, food and engineering factories.

The animal protection cell had filed a complaint with the Maharashtra Pollution Control Board, which said the dogs that turned blue had gone into the river near the site of a company that used blue dye for a range of purposes.

"We have warned the company owners to ensure no animals can enter again and such an incident should not be repeated, a control board official said.

The company had also been told to immediately remove the dye it was discharging. "We have given the company seven days to clear the pollutants from the site. If it is not removed then we will issue a notice."

The animal protection cell's Chauhan said it was not known it other animals in the area were being affected, or even killed by the dyes.