We still have a big workload: Russian Foreign Minister Sergei Lavrov
A new US-Russia nuclear arms reduction treaty is unlikely to be signed this week, Russia's foreign minister says.
Sergei Lavrov accused the US of a "slowdown" in the negotiations in recent days to find a successor to the Cold War-era Start 1 treaty.
The treaty, which led to deep cuts in nuclear arsenals on both sides, expired on 5 December.
Officials on both sides had expressed hopes that a new deal could be agreed before the end of the year.
But Mr Lavrov played down suggestions that an agreement could be signed by both presidents when they attend the climate summit in Copenhagen.
"It's highly unlikely to happen in Copenhagen," he told a news conference in Moscow. "We still have a big workload - of a purely technical character - facing us."
He went on to say: "In the past couple of days we have noted a slowdown in the positions of the US negotiators in Geneva. They explain this by the need to receive additional instructions. But our team is ready for work.
"I believe that if Russian and US negotiators concentrate on implementing these remaining orders from the presidents, we will reach agreement within a pretty brief period."
US and Russia have agreed to continue observing Start 1 - which was signed by Mikhail Gorbachev and George Bush Senior in the final days of the Soviet Union - until they reach a new agreement.
Under a joint understanding signed in July, deployed nuclear warheads should be cut to below 1,700 on each side within seven years of a new treaty - a huge cut on Soviet-era levels.
Nonetheless, between them, the two countries will retain enough firepower to destroy the world several times over.