Atomstroyexport confirmed reports that Azerbaijani border officials had stopped the cargo from crossing the border with Iran.
"Azerbaijani border guards stopped the cargo at the Azerbaijan-Iranian border several weeks ago," Atomstroyexport spokeswoman Irina Yesipova said.
She said the border service, which are refusing to authorize the release of the seized freight, were citing instructions from department heads.
"This situation is unlikely to seriously affect the commissioning schedule, although a slight risk still persists," she said.
The representative said her company was in talks with border and customs officials.
The press service of Azerbaijan's State Customs Committee said it had no information that the cargo had been seized.
The Baku-based Trend news agency meanwhile quoted the customs service as saying that the equipment did not have special permission from the Azerbaijan government to be transited through Azerbaijan.
Russia delivered its final and eighth fuel shipment to Bushehr on January 28. Russia has supplied a total of 82 metric tons of low-enriched uranium to the light-water nuclear power plant. Iran hopes its first nuclear power plant will be launched in October.