Andhra Pradesh Forensic Science Laboratory chief K P C Gandhi has said the derailment of the Hyderabad-Bangalore Express was a clear case of "sabotage".

A forensic team had on Sunday collected fresh samples of metallic powder of the tracks and the damaged rails for chemical analysis.

"The basic findings from forensic evidence so far suggests that the rail was not broken naturally but it was cut. Some implements found near the accident site are also being checked," Gandhi said. "Our investigations centre on what implements were used for cutting the rail, whether it was hacksaw or something else. It [cutting] was done not at one go but at different times."

The FSL director said that more forensic tests were required to establish the cause of the accident. "It is a priority case. It will take a day or two [to come out with details]. Since it is a complicated case, we have to do more than one test."

Meanwhile, the Crime Investigation Department would take up investigation to ascertain the exact cause for the mishap in the wake of controversy regarding sabotage, CID Additional Deputy General M L Kumawat said.

In all 19 people were killed and 87 injured when nine bogies of Hyderabad-Bangalore Express derailed at Ramlingayapalli in Kurnool district in the early hours of December 21.

Chief Minister N Chandrababu Naidu expressed his displeasure over the spate of statements made by the police and railway officials about the possible cause of the accident. "It is not proper for them [officials] to make statements in a sensitive case like this when the matter is under investigation."