Russia and the United States failed to narrow their differences over Washington's plans for a missile shield in Europe yesterday, but both said they were committed to replacing a Cold War pact on strategic arms.

After the talks, Russian Deputy Foreign Minister Sergei Ryabkov told journalists he was looking forward to working with the new US administration under President-elect Barack Obama and was confident a deal could be reached to replace the Start-1 pact, which expires next year.

"The task is quite realistic, we have enough time," he said. "I can't help being optimistic about that."

The Start treaty, signed by Moscow and Washington in 1991, committed both to cutting their numbers of missiles and strategic bombers to 1,600 each. Both sides met limits set by the treaty by December 2001.

In a telephone interview, the top US official at the talks, Under-Secretary of State for Arms Control and International Security John Rood, agreed that the two wanted a replacement for Start by the end of 2009.

"But there are substantial differences on our points to the final package," he said. Considerations on what should follow Start have been marred by growing differences between Moscow and Washington on arms control, dominated by Washington's plans for a missile shield in Europe.

Russia rejects US reasoning that interceptor missiles in Poland and a radar in the Czech Republic are needed to avert potential missile strikes from Iran.