WASHINGTON -- U.S. and Russian officials will meet in Geneva next month to discuss whether to extend a treaty limiting nuclear arsenals that expires late next year, the State Department said Friday.

The Russian government has been asking whether Washington is serious about replacing the Strategic Arms Reduction Treaty, signed in Moscow in 1991, which set ceilings on the size of the Russian and U.S. nuclear arsenals.

The two countries have already held extensive discussions about a post-START agreement, "and we expect to continue those discussions," the State Department said in a statement. "The parties to a START will meet in Geneva in mid-November to initiate this process."

The parties were obligated to meet no later than a year before the START treaty expires next December to begin consideration of whether or not to extend the treaty.

State Department spokesman Gordon Duguid said he thought the meeting would be held at the "working level" -- meaning senior officials below Cabinet level.

Foreign Minister Sergei Lavrov said this month that Washington was upsetting the nuclear arms balance by failing to offer a replacement for START. He said this was needed more than ever as the United States is planning to place elements of a defensive missile shield in Poland and the Czech Republic.

The United States contends that the missile shield is needed to protect against possible missile attacks from what it calls rogue states, specifically Iran.

Already tense relations between Russia and the United States worsened after Russia's military intervention in its former Soviet neighbor Georgia in August.

Washington shelved a deal on civil nuclear cooperation with Russia after the Georgia conflict, but the two countries have kept up discussions on issues like dismantling North Korea's nuclear program and pressing Iran to suspend its nuclear work.

Daryl Kimball, executive director of the Arms Control Association, said he did not think that a new post-START agreement was possible before President George W. Bush leaves office in January, but Moscow and Washington could agree to extend the treaty's main provisions until a new accord is reached.

"It will take a new administration to bridge differences and find a new replacement for START," Kimball said.

Both presidential candidates, Democrat Barack Obama and Republican John McCain, have expressed support for pursuing arms control agreements with Russia.