Russian President Vladimir Putin refused to set a date Tuesday for the start-up of Iran's first nuclear power plant, but stressed that Moscow would not back out of its commitment to complete the project.

After talks with Iranian President Mahmoud Ahmadinejad, Putin said revisions to the US$1 billion contract to build the plant in the Iranian port of Bushehr are necessary to clarify certain legal aspects and financial obligations by each side.

"I only gave promises to my Mom when I was a small boy," Putin told Iranian reporters, when asked whether he could promise that the plant that Russia is building would be launched before his term ends next May.

At the same time, he said, "We are not going to renounce our obligations."

Putin's careful stance suggested that Russia is seeking to preserve solid ties with Iran without angering the West. A clear pledge by Putin to quickly finish the plant would embolden Iran and could complicate international talks on the standoff over Iran's nuclear program.