Russia's nuclear power chief cancelled a Sunday visit to Tehran that was planned to prepare the nuclear fuel operation of the joint Bushehr power plant in southern Iran, ISNA news agency reported.
An official source told ISNA that Sergei Kiriyenko will instead meet his Iranian counterpart Gholam-Reza Aqazadeh next month in Vienna, the dpa reported.
No reason was given for the cancellation of the visit.
There have been reports that Russia might use the dispute over Iran's nuclear programmes - vetoing further sanctions against Tehran - as a pressure tool against the West in the current tensions over Georgia.
Instead of Kiriyenko, a delegation from the Russian nuclear power construction company Atomstroyexport will come to Tehran on Sunday to discuss the Bushehr nuclear power plant and also visit the site itself, ISNA said.
Russia finished delivery of 82 tons of low-enriched uranium for the plant's light-water reactor in January, and Kiriyenko said in June that nuclear fuel operations would start this year.
Aqazadeh said the Russian side was committed to launching the Bushehr plant as scheduled.
The 1-billion-dollar joint project was originally supposed to be completed at the beginning of the millennium but has been delayed at least five times for various reasons.