Russia and the United States will sign a long awaited civilian nuclear cooperation pact on Tuesday, the last full day of Vladimir Putin's presidency, a Russian official said.
The deal will allow the former Cold War foes to widen cooperation in areas such as a uranium bank and the storage of nuclear materials and let them work together on advanced reactor programmes.
"The agreement will be signed on Tuesday in Moscow," the official said on condition his name was not used. "It is symbolic that it will be signed on the last day of Vladimir Putin's presidential term."
At the 2006 Group of Eight summit in St Petersburg, US President George W Bush and Putin asked their governments to move forward on the deal but it has faced opposition from some US congressmen.
The Russian source said Sergei Kiriyenko, chief of Russian state nuclear corporation Rosatom, and US Ambassador to Russia William Burns would sign the document.
A 123 agreement, so-called because it falls under Section 123 of the Atomic Energy Act, is required before countries can cooperate on nuclear materials.
Some US politicians have said nuclear cooperation with Russia should be shunned because Russia is helping Iran build an atomic power station in Iran, but the Bush administration is keen to have the pact approved this year.
Once the agreement is signed Bush will have to send it to Congress, which has 90 days to act. If Congress does nothing, the agreement goes into effect. If lawmakers want to block it, they must pass a resolution of disapproval.