The IAEA reports thousands of pieces of nuclear materiel have gone missing over last three decades.

The United Nations’ nuclear watchdog has called for “vigilance” as it warned of thousands of instances of radioactive materials going missing.

The International Atomic Energy Agency’s (IAEA) Incident and Trafficking database reported on Monday that 31 countries reported 168 incidents in which nuclear or other radioactive material was lost, stolen, improperly disposed of or otherwise neglected last year, “in line with historical averages”. The watchdog has recorded more than 4,200 thefts or other incidents over the past 30 years.

The IAEA noted that six of last year’s incidents were “likely related to trafficking or malicious use”, also known as Group I, representing a slight increase from 2022 but a drop from 2021.

The trafficking database covers three types of incidents where nuclear or radioactive material escaped regulatory control, with Group I being the most serious.

Incidents where trafficking or malicious use is unlikely or can be ruled out are known as Group II and those where any connection is unclear fall into Group III.

The trafficking database was set up to track the illicit trafficking of nuclear material, such as uranium and plutonium, which can be used in atom bombs, and radioactive material, such as isotopes used in hospital equipment.

The IAEA released its latest finding as it opened its fourth international conference on nuclear security, which will run until Friday in the Austrian capital, Vienna.

Since 1993, the nuclear watchdog has recorded 4,243 incidents, 350 of them connected or likely to be connected to trafficking or malicious use.

“The reoccurrence of incidents confirms the need for vigilance and continuous improvement of the regulatory oversight to control, secure and properly dispose radioactive material,” said Elena Buglova, director of the IAEA’s nuclear security division.

The IAEA noted a decline in incidents involving nuclear material, such as uranium, plutonium and thorium.

However, Buglova warned dangerous materials remain vulnerable, especially during transport, stressing the “importance of strengthening transport security measures”.

A total of 145 states currently report to the IAEA about incidents that involve nuclear or other radioactive material lost, stolen, improperly disposed of or otherwise neglected.