This is stated in the IAEA published report on the results of the mission to the Zaporizh* NPP.

The report indicates that there are several military trucks on the ground floor of turbine halls in power units Nos. 1, 2.

38. On 2 September, the team verified that all safety systems for Unit 6 were in normal condition during the visit to the main control room of Unit 6. [CAPTION: Military vehicles on the ground floor of the turbine hall of Unit 2 of ZNPP (Photo: IAEA)]
39. The [ISAMZ] team observed the presence of Russian military personnel, vehicles, and equipment at various places at the ZNPP, including several military trucks on the ground floor of the Unit 1 and Unit 2 turbine halls and military vehicles stationed under the overpass connecting the reactor units. The team also observed the presence of an expert group from Rosenergoatom. It was explained to the team by the Ukrainian plant staff and managers that the role of this expert group was to provide advice on nuclear safety, security, and operations to the management of the ZNPP. [pp 13-14]

IAEA believes that the presence of senior technical personnel can lead to interference in the normal operation of operational management and create potential friction in the context of decision-making, the report notes....

Source:  Zelensky's video message
Direct speech: "Regarding IAEA Director General Grossi's proposal to create a protection zone at the station, one must look at the specific content of such an instrument: what exactly can be protection?

If the content of this proposal is to demilitarize the territory of the nuclear power plant—and this is logical, because it was the Russian military presence that put the Zaporizh* station on the brink of a radiation disaster—then we can support such a demilitarized protection zone....