The Russian-Iranian talks held in Moscow March 7-9 on Tehran's outstanding debt for the Bushehr NPP construction produced no positive results, an Atomstroyexport spokesman said.
"The parties failed to make final decisions on this issue. The talks are expected to be resumed next week in Tehran," the spokesman said.
Russian specialists are completing the construction of Iran's first NPP under a $1 billion contract signed in 1995, but Russia claimed last month that Iran had an unpaid debt for its construction services, and said that as a result construction might take longer than previously expected.
The Bushehr facility has been a source of international dispute, with the United States and other Western countries raising concerns that Iran could use the project as part of a covert weapons program. Iran has consistently denied that its nuclear program has military goals.
The UN Security Council adopted a resolution in December imposing sanctions against Iran.
Russia, a key economic partner of Iran, has consistently supported the Islamic Republic's right to nuclear power under the Nuclear Non-Proliferation Treaty (NPT), and has resisted the imposition of harsh sanctions.