At least 11 workers have died after a fire broke out among tents at a construction site in the Turkish city of Istanbul.

The workers were living in a giant tent on the site of a shopping mall under construction, where the fire broke out late on Sunday, Necmi Kadioglu, the mayor of Istanbul's Esenyurt district, said.

"Between 11 and 14 workers are believed to have died in the fire," Kadioglu told the Turkish state-run TRT television from the site of the blaze.

"This is the site of a shopping mall. It appears the fire has something to do with the heating problem as it is freezing here and right now it is minus one degree."

Authorities suspect that the fire might have originated from an electrical heater, Kadioglu said.

While the cause of the blaze has not yet been established, media reports suggested it may have been caused by a short circuit.

Firefighters put out the flames as ambulances attended the scene, the private NTV television reported.

Working under floodlights despite the snow, the firefighters managed to recover the bodies of the workers from the mangled ruins of the tent.

An adjacent tent was also burned but it was not clear if any of the workers were sleeping there.

Istanbul, Turkey's commercial hub, is home to more than 13 million people and a site for many massive construction projects. 

About 200 people are working at the construction site where the fire broke out.

Source: Agencies