Ukraine's nuclear energy operator

said Russian forces were performing secret work at the occupied Zaporizhzhia nuclear plant, amid the exchanged blame over preparing to launch a "dirty bomb." Energoatom said Russia has carried out secret construction work over the last week at the EU's largest nuclear power plant.

• On a related note: Russia is asking the UN Security Council to investigate its claims that Ukraine and the US are violating the banned use of biological weapons by carrying out activities at biological laboratories in Ukraine, in a draft resolution.