NATO and Russia failed Wednesday to reach a breakthrough on a missile shield project in Europe with the Russian defence minister complaining that Moscow's demands were falling on deaf ears.

After talks between NATO defence ministers and their Russian counterpart in Brussels, NATO Secretary General Anders Fogh Rasmussen dismissed Russian demands for a legal guarantee that the project was not directed at Russia.

"It would be in the interest of Russia to engage in a positive cooperation with NATO and focus on real security challenges instead of some ghosts of the past that don't exist anymore," Rasmussen said.

Russian President Dmitry Medvedev agreed at a NATO summit in November to explore the possibility of cooperating with the former Cold War foe on a system to protect Europe's population from the threat of ballistic missiles.

Fearing that the system would undermine its nuclear deterrent, Moscow has since then demanded a legally binding guarantee that the missile shield was not aimed at Russia.

The Western military alliance has also rejected Medvedev's idea of dividing the European continent into sectors of military responsibility, with Rasmussen saying the two sides should keep their systems separate.

"NATO is not hearing us for the moment," said Russian Defence Minister Anatoly Serdyukov. "NATO's position is not acceptable to Russia," he said, adding however that Russia still hoped to reach an agreement.

Despite the lack of a breakthrough, Rasmussen said he was optimistic that a deal could be reach in time for the next NATO summit hosted by the United States in May 2012.

"The Russians have their positions and their interests, we have our positions and our interests, and now the political challenge is to build a bridge and we still have some time," he said.

"I would expect us to make steady progress. It would be hard work but I'm still optimistic. I think at the end of the day we can reach a solution."

In the meantime, NATO defence ministers adopted an action plan on Wednesday to forge ahead with the missile shield project, which an alliance official said is expected to be completed by 2018.