MOSCOW - Russian Prime Minister Vladimir Putin said on Thursday he hoped for improved relations with the United States in 2010, days after his attack on U.S. missile defense plans displayed the fragility of efforts to draw closer.

In a New Year greeting, Putin praised U.S. President Barack Obama's efforts to reset ties, which had reached their lowest point since the Cold War under George W. Bush.

I sincerely hope that this positive approach will allow us to find optimal solutions to even the most complex questions on the bilateral agenda, Putin said in the message.

Putin, Russia's pre-eminent politician, criticized the United States on Tuesday for not giving Moscow enough information on its reformulated shield plans, and linked the plans to agreement on a new nuclear arms pact.

In a speech in the Far Eastern city of Vladivostok, Putin described the planned anti-missile system as a problem and warned that Russia would respond by developing new weapons of its own to maintain a military balance.

In September, Obama said the United States would scrap parts of George W. Bush's missile defense plans, a step seen as an attempt to allay Kremlin fears that the system was a direct threat to Russia.

Obama's revised anti-missile plans are based on sea- and land-based missile interceptors in Europe.

Moscow has previously voiced some unease with the vagueness of the new scheme but before Putin's comments it was not directly tied to agreeing a successor to the 1991 Strategic Arms Reduction Treaty (START I).

Russia and the United States failed to agree on a successor to START I by December 5, when the treaty was due to expire, and have extended it as they try to work out a new agreement.

Putin also congratulated Obama on his Nobel Peace Prize and said they must work together on other issues.

It is also important to intensify joint efforts to settle the most sharp international and regional problems, said Putin, without elaborating.

(Reporting by Conor Sweeney; editing by Tim Pearce)

Russia George W. Bush Barack obama Vladimir putin