The United States vowed on Saturday to press ahead with plans to build a missile shield in central Europe, but only if it was proven to work and was cost effective.

Russia has objected to the plans but its Deputy Prime Minister Sergei Ivanov has said that Moscow would not start its own new missile deployments if Washington reviewed it.

Speaking at a European security conference in Munich, U.S. Vice President Joe Biden reiterated that work on missile defences would continue "in consultation with our NATO allies and Russia".

"We will continue to develop missile defences to counter a growing Iranian capability, provided the technology is proven and it is cost-effective," he said.

Speaking at the same conference on Friday, Ivanov said Moscow was eager to hold talks on the shield with the Obama administration and was open to a joint assessment of threats with the United States.

Biden and Ivanov are due to meet in Munich on Sunday.

Former U.S. President George W. Bush sealed deals last year to deploy 10 interceptor missiles in Poland and a radar in the Czech Republic. Moscow condemned the plan and threatened to put its own missiles near the Polish border in response.

NATO's Secretary-General Jaap de Hoop Scheffer said the 26-nation U.S.-led alliance was willing to include Russia in talks on missile defence but said he did not consider talks on a new security architecture sought by Moscow would be possible unless Moscow abandoned old thinking.

COOPERATION WITH RUSSIA "DOABLE"

"I think real transatlantic cooperation on missile defence including Russia is very doable and would, I think, make those who might threaten Europe with missiles think twice," he said.

He said he backed the idea of discussions Russian President Dmitry Medvedev has proposed on a broader Euro-Atlantic security architecture, which many NATO allies have expressed a willingness to take part in.

However he added: "I cannot see how we can have such a serious discussion of such a new architecture, in which President Medvedev himself says territorial integrity is a primary element when Russia is building bases inside Georgia, a country that doesn't want those bases.

"That cannot be ignored and it cannot be the foundation of a new European security architecture," he said.

De Hoop Scheffer was also concerned that Kyrgyzstan had announced in Moscow this week plans to close a U.S. air base used to supply forces in Afghanistan, saying this was at least "incongruous" with Russian support in other ways for the international operation there.

"We ... need to move beyond a 19th century 'Great Game' idea of sphere of influence," he said.

Czech Deputy Prime Minister Alexandr Vondra, whose country would host part of the U.S. shield along with Poland, also said the United States and central European countries should cooperate with Russia on the plans but Moscow could not have a veto.

"It is important to develop the future missile defence system," he said, saying it would protect Western countries from Middle East threats. "Russia should be invited to this cooperation but must not have a veto over it."

Polish Prime Minister Donald Tusk said he reiterated his county's willingness to host the system in a meeting with Biden.

"The Vice President was very clear in our conversation that the position of the U.S on the (missile shield) project has not changed," he said. "We will be consulted on the matter and we should have further information in a matter of tens of days."