Washington: The United States said on Thursday it had made some progress in two days of talks with Russia over a disputed missile shield it proposes to deploy in Europe to deter attacks from states like Iran, but big differences remained.

The latest talks in Washington followed a visit last week to Moscow by US Secretary of State Condoleezza Rice and Defence Secretary Robert Gates, who offered to give Moscow access to proposed shield sites in the Czech Republic and Poland as a way of allaying Russian fears over the plan.

"We made a lot of headway but there are still significant issues that need to be resolved," Acting US Undersecretary of State for Arms Control and International Security, John Rood, told reporters at the end of the talks.

Both sides discussed written proposals on missile defence and other key bilateral issues Rice and Gates had sought to bring up at the end of their Moscow trip.

Preparation for summit

Washington wants to clinch a so-called strategic framework agreement on key issues between the two countries in time for a summit next month between US President George W. Bush and outgoing Russian President Vladimir Putin, but US officials conceded there was still some way to go.

Asked whether he thought the strategic framework document, which includes missile defence, would be agreed on before the Putin-Bush summit, senior State Department official Dan Fried told reporters: "I don't know."

"They were not going to give away positions where they had disagreements, but they were not throwing up roadblocks and spinning things out," Fried added.

Rood said the two sides were working at an "intense" pace, but he was noncommittal over when there might be agreement.

"I often find it difficult to predict when my counterpart will finally reach a meeting of the minds with me. It is always a difficult challenge," he said.

The US plan to place parts of a missile defence system in formerly Soviet-allied countries has been a major factor in the deterioration of US-Russian relations in recent years.

The latest American proposals under discussion are meant to convince Moscow that the missile defence system in Eastern Europe would not be directed against Russia, US officials said.

Bush, whose term ends in January 2009, is set to meet Putin in early April in Sochi, following a Nato summit in Romania.

"It is important that both countries complete a presidential transition - that is Russia and us. We thought it was important to have this (strategic framework) document as a positive platform in the US-Russian relationship as we go forward," Fried said.