PITTSBURGH, September 26 (RIA Novosti) - Russia and the United States have agreed to jointly participate in the preparation of the nuclear security summit in Washington in 2010, the Russian president said on Saturday.

"There is an agreement that we will be participating in the preparation of the summit on the nuclear security, which will be held in Washington [D.C.] in 2010," President Dmitry Medvedev said at a news conference following the G20 summit in Pittsburgh.

The Russian president also said he hoped that a new Russian-U.S. strategic arms reduction treaty would be ready before the yearend.

"We hope that we will manage to agree by December, but the process is difficult," he said.

Medvedev and U.S. President Barack Obama agreed in July in Moscow on the outline of a deal to replace the 1991 Strategic Arms Reduction Treaty (START 1), which expires on December 5, including cutting their countries' nuclear arsenals to 1,500-1,675 operational warheads and delivery vehicles to 500-1,000.

The START 1 treaty obliges Russia and the U.S. to reduce nuclear warheads to 6,000 and their delivery vehicles to 1,600 each.

In 2002, a follow-up agreement on strategic offensive arms reduction was concluded in Moscow. The document, known as the Moscow Treaty, envisioned cuts to 1,700-2,200 warheads by December 2012.

According to a report published by the U.S. State Department in April, as of January 1 Russia had 3,909 nuclear warheads and 814 delivery vehicles, including ground-based intercontinental ballistic missiles (ICBM), submarine launched ballistic missiles (SLBM) and strategic bombers.

The same report said the United States had 5,576 warheads and 1,198 delivery vehicles.