A Russian government news agency says a nuclear plant being built for Iran will not become operational before September 2008 at the earliest.

The RIA-Novosti report Wednesday says the Bushehr power plant is at least one year behind its original schedule because of payment disputes with Iran. Iran claims that the plant could be operational in September of this year.

A spokeswoman for Russia's state-firm, Atomstroiexport, says a shortage of payments from Iran has undermined the confidence of the project.

The head of Energoprogress. Ivan Istomin, a sub-contracting company working with Atomstroiexport, said that launching the plant this year is "unrealistic." Russia says the project has also been stalled because of delays in shipping parts for the plant from other countries.

Bushehr is Iran's first nuclear power plant.

Tuesday, the United Nations' nuclear agency said it will inspect Iran's heavy-water nuclear reactor under construction in Arak early next week.

Iran agreed two weeks ago to allow inspections by the end of this month as part of an agreement aimed at resolving questions about its nuclear activities.

The U.N. Security Council has already imposed two sets of sanctions on Iran because of its refusal to suspend uranium enrichment, and there are calls for more.