“Such abandonment is against our regulations,” OAP deputy secretary general Kittisak Chinudomsub said yesterday. He said any holder of a permit to own radioactive substances would be punished – by having their permit revoked – for doing that.

“But if the investigation finds that the person who abandoned |the case owned it without a permit, he will be liable to legal punishments of up to one year in jail and/or a fine |of up to Bt10,000,” Kittisak said.

He said the metal case itself, even without the radioactive substance inside, was worth hundreds of thousands of baht. It was unusual that the owner would not want the case, he thought, because it could be used to keep other radioactive substances.

When the case was found inside the building, which was about to undergo renovation on Thursday, fear spread among people nearby because it was labelled with a radioactive warning sticker. But it was confirmed shortly after by the OAP that there had been no leak of radiation.

OAP secretary general Dr Atchara Wongsaengchan reiterated yesterday that the public could be assured that no leak had occurred.

The substance was discovered yesterday sealed in a small metal box with a radioactive warning sticker.

Police and Office of Atoms for Peace (OAP) officials inspected the item in the two-storey building for any leakage and sealed off the area as a safety precaution.

The building was previously leased to a South Korean company, it was reported.

At 4.20pm OAP officials revealed the substance was iridium-192, a radioactive isotope, and there was no trace of radioactive leakage at the scene.

Police collected evidence and passed the item onto OAP for its safe transport.

Acting city police chief Lt-General Sanit Mahathaworn inspected the scene later in the evening.

The iridium-192 expired in 1995. According to an expert, iridium-192 is used in gamma ray photography and to detect pipe cracks or leakages.

The International Atomic Energy Agency defines iridium-192 as a category two radioactive substance, meaning it can kill people in close proximity to it within hours to days.