According to a statement made on Monday, the U.N. nuclear watchdog is planning to send inspectors to two Ukrainian locations in the next days at Kiev’s request. This is presumably in response to Russian assertions that Ukraine may use a so-called dirty bomb, which Ukraine denies.

The International Atomic Energy Agency made its disclosure in response to claims made by a senior Russian official that two nuclear-related institutions in Ukraine were working to build such a bomb. Nuclear material is mixed into “dirty bombs.”

“The International Atomic Energy Agency (IAEA) is aware of statements made by the Russian Federation on Sunday about alleged activities at two nuclear locations in Ukraine,” the IAEA said in a statement, adding that both were already subject to its inspections and one was inspected a month ago.

“The IAEA is preparing to visit the locations in the coming days. The purpose of the safeguards visits is to detect any possible undeclared nuclear activities and material,” it added.