At least 39 people were killed and 50 others  injured when nine coaches of a Express train derailed in Vizianagaram district of the south Indian state of Andhra Pradesh on Saturday night, reports said.

Nine coaches and the engine of the Jagdalpur-Bhubaneswar Hirakhand Express train derailed near Kuneru station in Vizianagaram district at around 11 pm, reports said.

Relief and rescue operations were put into force by administration immediately and the railways issued a list of helpline numbers.

Meanwhile, the Railways has started a probe into the accident as they suspect it to be an act of sabotage, news agency PTI said.

"There is a strong indication of tampering with the track as the area is known to be a Naxal-prone zone," it quoted officials as saying.

"Earlier, a goods train had safely passed the same track. The patrol man had also checked the track. However, the driver of the train heard a big cracker-like sound just before the derailment and there appeared to be a big crack on the track which caused the derailment,” the officials said.