On the eve of President Barack Obama's first visit to Moscow, Russia and the United States were on Sunday still bargaining on an outline deal to cut Cold War arsenals of nuclear weapons.

Obama arrives on Monday to meet Kremlin chief Dmitry Medvedev at what is being billed as a summit that could "reset" US-Russia relations after they hit a Cold War low under George W Bush.

But, in comments which underline continuing deep differences between Washington and Moscow, Medvedev said in an interview published on Sunday that the United States must compromise on plans to deploy an anti-missile system in Europe.

This was necessary to get a deal to replace the 1991 Strategic Arms Reduction Treaty (START I) before it expires on Dec 5, the Russian leader said.

"We consider these issues are interconnected," Medvedev said in an interview with Italian media that was broadcast on Russian state television Sunday.

"It is sufficient to show restraint and show an ability to compromise. And then we can agree on the basis of a new deal on START and at the same time can agree on the question of how we move forward on anti-missile defence," he said.

Russia's Interfax news agency quoted a highly placed source in the Moscow Foreign Ministry as saying that a so-called framework agreement the presidents were due to sign on nuclear cuts is not yet ready, less than 24 hours before Obama arrives.

The framework deal was supposed to be the centrepiece of Obama's visit to Moscow, where he will also meet Prime Minister Vladimir Putin, who has repeatedly warned the United States that Russia would not accept plans for the missile system in Europe.

Obama and Medvedev in April instructed negotiators to work on a new treaty but negotiations were continuing through the weekend to find a deal.

Washington plans to station anti-missile batteries and radar detection systems in the Czech Republic and Poland as part of a global system to spot and shoot down hostile enemy rockets before they reach the US.

Moscow, which relies heavily on nuclear weapons for its defence because of the poor state of its conventional weapons, opposes the anti-missile system as a threat to its security. It dismisses US arguments that the system is directed only at Iran, saying it could also be used against Russia.

Obama has said the United States government is reviewing  missile defence ideas but that Washington needs to build a system which could defend the United States and European allies from a potential nuclear attack from Iran.

"When discussing our plans for Europe, we first and foremost are seeking to build a missile defence system that protects the United States and Europe from an Iranian ballistic missile armed with a nuclear warhead," Obama told Russia's Novaya Gazeta in an interview to be published on Monday.

"We have not yet decided how we will configure missile defence in Europe. But my sincere hope is that Russia will be a partner in that project," Obama said.

Medvedev said Moscow could not tolerate an anti-missile system that "in essence is directed against ... Russia" but that the Kremlin was willing to work on a global defence system in collaboration with other powers. - Reuters