Russia would be willing to discuss a new missile defence structure with the United States but sees Iran's nuclear programme as a separate issue, Russian President Dmitry Medvedev said on Tuesday.

Asked about a report in the New York Times that U.S. President Barack Obama had written to him offering to back off deploying a new missile system in Eastern Europe in return for help with the Iranians, Medvedev said signals from Washington were positive but the two issues were separate.

"If we are talking about any "swaps" (Iran for missile defence), this is not how the question is being put. This would not be productive," Medvedev told a news conference in Madrid, where he was on a state visit.

But he added: "If the new (U.S.) administration shows common sense and offers a new (missile defence) structure which would satisfy European (needs) ... and would be acceptable for us, we are ready to discuss it."

"I count on positive signals we are now receiving from Washington translating into agreements," Medvedev said.

Russia opposes the deployment of a U.S. missile defense system in Poland and the Czech Republic. The system was proposed by the administration of former President George W. Bush.

The Russian president did not directly refer to any letter from Obama. His spokeswoman confirmed he had received it.

"We have received this letter. It was in fact a reply to a letter from Medvedev sent to Obama after his appointment. The letter contained an assessment of the situation, but there were no concrete proposals about any mutually binding decisions," Natalya Timakova told reporters in Madrid.

Moscow has not yet responded to the letter, according to the New York Times.

U.S. Secretary of State Hillary Clinton is set to meet with Russian Foreign Minister Sergei Lavrov in Geneva on Friday.