Russia and Iran on Sunday signed a protocol to iron out obstacles in the construction of Iran's first nuclear energy plant which has been delayed due to financial disputes.

Representatives of the Russian project operator Atomstroyexport and Iran's Atomic Energy Organization signed the agreement in Moscow on the Bushehr plant, the Interfax news agency said, citing Atomstroyexport press secretary Irina Yesipova.

Russia and Iran signed the 1-billion-U.S.-dollar contract for the plant, located in southwestern Iran, in 1995. But work at the plant has been long delayed.

Russia has alleged that Iran failed to pay on time but Iran denied that.

Under an agreement reached last September, nuclear fuel should be delivered to Bushehr last March and the plant will be put into use in September. But Russian officials said earlier this month that it will not send nuclear fuel to the plant until disputes were solved.

The problem will put off the trial operation of the facility by at least two months, Interfax said, citing Head of the Russian Atomic Energy Agency Sergei Kiriyenko.

"If (the protocol) is successfully implemented, part of the questions of financing will be settled," Yesipova was quoted as saying, noting the two sides will continue further talks in Tehranin May.