Russia is optimistic about ties with the United States next year, but wants a "positive shift" on Washington's controversial missile shield from Barack Obama, a top Russian diplomat said Thursday.

"I think in 2009 there will be more achievements than problems in Russian-US relations," Deputy Foreign Minister Sergei Ryabkov told reporters in Moscow.

"In general we are entering 2009, the year of a change of administration in the United States, the appearance of new figures in key posts in Washington, with a certain measured degree of optimism," he said.

However he also called on Obama to drop US plans to place missile defence facilities in Eastern Europe, a project that has been heavily promoted by outgoing President George W. Bush despite furious Russian objections.

The US president-elect, who is due to take office January 20, has yet to take a clear position on the missile shield.

Ryabkov also linked missile defence to talks on the renewal of START, a key nuclear arms control treaty that expires in December 2009.

"What we will have at the end of next year depends on many circumstances, above all how much of a positive shift in the US position we can establish in the START sphere and the missile-defence sphere," Ryabkov said.

Ryabkov also denied media reports that Russia was selling advanced S-300 surface-to-air missiles to US arch-foe Iran, calling them "information that does not correspond to what is happening or what could happen."

But he added: "S-300s are also a defensive system. This is a system which cannot be reconfigured in any way into an offensive weapon."

Russian officials have repeated denied selling offensive weaponry to Iran but Moscow has openly sold Iran defensive arms, such as Tor-M1 anti-aircraft systems, which have a shorter range than the sophisticated S-300s.

The reports of the S-300 sales come amid tension between Iran and the West over Tehran's nuclear programme, which the West fears could be used to develop nuclear weapons.

The United States and its ally Israel have never ruled out an aerial attack against Iran to thwart its nuclear ambitions.