A mild radioactive substance has gone missing from Oil and Natural Gas Corporation's (ONGC) base camp at Rajamahendravaram in Andhra Pradesh. The incident came to light during an internal audit on Thursday following which ONGC officials on Friday filed a complaint with the Bommuru police.

Officials identified the substance as Caesium-137 (CS-137) and while initial reports suggested that the quantity of the missing substance was unknown, officials later said it was only a few grams but was still worth Rs 27 lakh.

The isotope was said to be reported missing from a truck that transported it to the logging shed of the complex. 

According to media reports, the CS-137 was being carried in the vehicle along with another radioactive isotope AmBe-241(Americ um-241) and reached the shed on January 14. However, when officials opened the shutter of the shed on January 16, they found the CS-137 missing.

After local media reports began claiming that the missing substance was highly explosive and worth several crores, the ONGC was forced to release a statement, which said, “The missing material is used in the oil and gas exploration and it is not an explosive."

After the complaint was lodged, the police have formed four teams to try and trace the missing substance. 

According to the United States' Environmental Protection Agency (EPA), "Cesium is a soft, flexible, silvery-white metal that becomes liquid near room temperature, and the most common radioactive form of the substance is Cs-137, which is produced by nuclear fission. It is also one of the byproducts of nuclear fission processes in nuclear reactors and nuclear weapons."

The ONGC in the state has repeatedly witnessed leaks from gas pipelines that have resulted in panic and even evacuation of villages in the past. However, this is the first time that such an incident is being reported from the corporation.