MOSCOW, September 3 (RIA Novosti) - Russia and the U.S. are making headway on work to have a new nuclear arms reduction deal in place by the time the current treaty expires on December 5, Russian Foreign Minister Sergei Lavrov said on Thursday.

U.S. President Barack Obama and his Russian counterpart Dmitry Medvedev agreed in July in Moscow on the framework of a deal to replace the 1991 Strategic Arms Reduction Treaty (START-1).

Recent media reports have speculated however that Moscow and Washington have been unable to come to an agreement on reductions in delivery vehicles.

"There are a lot of issues that are quite complex in regard to the security of the Russian Federation and the United States, as well as issues of strategic stability," Lavrov said.

"However, we need to work in the timeframe the presidents defined and we will do everything we can to have the new document ready before the expiration of the current START treaty," he said.

Russia's top diplomat said that negotiators had made progress on some of these "complex" issues and would inform both presidents of what they achieved at the G20 summit in Pittsburgh on September 24-25.

"We will have something to report by Pittsburgh," Lavrov said.