Brussels: Russia and NATO remain deadlocked on a long-running dispute over the alliance's plan for a missile shield for Europe, officials said Friday, and Russia warned that time was running out for an agreement.

NATO's Secretary-General Anders Fogh Rasmussen reported no progress toward a deal on the contentious issue, following a key discussion among alliance foreign ministers and Russia's Foreign Minister Sergey Lavrov that came amid political turmoil in Russia and tart criticism of the United States.

Fogh Rasmussen rejected Russian criticism that NATO is ignoring its concerns that the planned missile system might one day be turned on Russia. He said discussions with Russia will continue and he expressed optimism for an initial deal before NATO's next global summit, in Chicago in May 2012.

"We listen, and we have listened today," Fogh Rasmussen told journalists after the meeting with Lavrov at NATO headquarters.

Lavrov, who speaks perfect English, spoke in clipped Russian immediately after Rasmussen.

"Unfortunately our partners are not yet ready for cooperation on missile defense," Lavrov said.

He left the door open for more talks, "provided that legitimate concerns of all parties are taken into consideration."

Russia has insisted on a treaty that would be binding on the United States and its allies, guaranteeing that the anti-missile system would in no way threaten Russia's own ballistic missiles. The US has said it's willing to adopt a nonbinding written agreement, but that a treaty is unworkable.