Russia says it will undertake a key step next week towards starting a reactor at Iran's first nuclear power station.
The state atomic corporation, which is building the plant, says engineers will begin loading the Bushehr reactor with fuel on 21 August.
Bushehr will then be considered a nuclear installation.
However, the BBC reports it could be six months before the reactor is fully operational.
Russia will run the plant, supply the fuel and take away the fuel waste.
Russia has been helping build the plant since the mid-1990s, amid tensions over Iran's nuclear programme. The project was started 35 years ago, under the Shah.