Poland on Monday urged NATO's new secretary general to push ahead with a missile shield system amid the West's worst standoff with Russia since the Cold War.

"We firmly support the creation of this (missile shield) system as a pan-NATO one because only this makes deep sense both politically and in terms of defence," Poland's President Bronislaw Komorowski said at a joint press conference with NATO Secretary General Jens Stoltenberg.

"Poland is determined to build its missile shield and air defence system -- it's important not only for Poland -- and we uphold our obligations for the US portion of this project," Komorowski said.

Stoltenberg, who chose Warsaw for his first foreign visit, said Poland "was a key contributor to our missile defence system."

The new NATO chief said last week that Russia must reverse course in Ukraine but stressed that the alliance remains ready to have a constructive relationship with Moscow.

Poland said last year it would spend 33.6 billion euros ($43.3 billion) to set up its own missile shield.

NATO's 28 members decided in 2010 to create a missile shield based on US technology. The project is due to be completed in 2020, with significant elements in Romania and Poland.

The Western defence alliance insists the role of the planned shield is a "purely defensive" response to external threats, notably from so-called "rogue states", and is in no way directed against Russia.

But Moscow has taken a dim view of the project, seeing it as a security threat on its very doorstep.

The escalation of tensions with Russia since January over its role in the Ukraine crisis has sounded the alarm on NATO's eastern flank in countries that were under Moscow's thumb during the Soviet era.

Tension mounted further after Russian President Vladimir Putin was quoted last month as saying that "if I wanted, Russian troops could not only be in Kiev in two days, but in Riga, Vilnius, Tallinn, Warsaw or Bucharest, too."

Stoltenberg, who took over as NATO chief last week, insists that Russia must reverse course in Ukraine but stressed that the alliance remains open to a constructive relationship with Moscow.