At least 29 people have died in a fire in an Istanbul nightclub.

The fire broke out during the day, after the popular club was closed for renovations during the month of Ramadan.

The nightclub, called Masquerade, is split over two floors in a 16-story building, in the heart of Istanbul. Governor of Istanbul, Davut Gül, said that "the fire broke out in the afternoon for an unknown reason.

It appears that the victims of the fire were workers renovating the nightclub." Five people were arrested on suspicion of negligence or involvement in the fire, including the nightclub manager and the director of renovations.

The authorities in Istanbul opened an investigation, in an attempt to find out the cause of the fatal fire, while the gas and electricity systems in the region of the nightclub were closed for fear of secondary explosions.

Istanbul Mayor Ekrem İmamoğlu said the nightclub's owners had not applied for a building and renovation permit.

"No application was submitted to the local municipality for any renovation or construction at this location, and since the club is located two stories below ground level, the work was not visible," İmamoğlu said.