Russia-U.S. weapons talks on track: Kremlin adviser

President Barack Obama greets Russia's President Dmitry Medvedev (L) at the Phipps Conservatory for an opening reception and working dinner for heads of delegation at the Pittsburgh G20 Summit in Pittsburgh, Pennsylvania September 24, 2009.

MARRAKESH, Morocco (Reuters) - Russia and the United States are on track to sign a new deal to reduce their arsenals of nuclear weapons by the time a previous agreement expires next month, a Kremlin aide said at a policy conference in Morocco.

The Strategic Arms Reduction Treaty known as START-1 runs out on December 5 and negotiators have been working to prepare a new detailed treaty to be signed by the two nations' leaders.

President Barack Obama and Kremlin chief Dmitry Medvedev agreed in July on the outlines of a preliminary deal to replace the landmark 1991 treaty but negotiators are still working through several technical issues.

"We are still optimistic about ... signing a new agreement this year which will imply huge progress for the world in this matter," Arkady Dvorkovich, a top adviser to Medvedev, said at a World Policy Conference in Marrakesh.

"We have a very good and constructive dialogue right now on this matter. I think the obstacles are mostly technical and we can complete in time," he said late on Saturday.

Talks on the pact may have been facilitated by President Barack Obama's decision to roll back the plans of his predecessor George W. Bush for a missile shield in Eastern Europe by deploying a radar in the Czech Republic and interceptor missiles in Poland.

(Reporting by Tom Pfeiffer; editing by Michael Roddy)